engine stuttering and low key freaking out

[Antonio9M]

ANY INSIGHT IS APPRECIATED! currently low key freaking out.
post w/ VIDEO: https://www.reddit.com/r/Yamaha/comments/l5quri/engine_stuttering_and_low_key_freaking_out/

coming back form doing the groceries, my 2014 Yamaha Bolt just started to sputter and stutter (maybe cough and seize? idk which is which), was on the throttle doing 30mph/50kph when the throttle would die down a bit or jerk around and engine sound would be a deep rumble, and eventually it would get to the point where I wouldn't receive enough power so would go through the gears, slow down and after a bit of that, would have to pull over, and start the engine up again. I had to do this twice, every 7 min or so.
Just finished a 650mile/1,050km road trip a week ago, where I had oil leaking out from my air filter due to (probably) excessive oil, had poured extra oil b4 I had left. After taking some oil out, no more was coming out, and running smooth.
Then I changed my oil yesterday, oil was a deep brown, and put in around 4 quarts/3.79 L of oil in. 3 quarts/bottles were of one brand, 1 quart/bottles was another (does this matter??). I need to change my oil filter as well. Previous oil was NON synthetic, this time around it was 100% synthetic
Googled, and found that a probable cause is a clogged air filter (oil leakage from road trip?) https://motorcyclehabit.com/5-reasons-why-your-motorcycle-is-sputtering/ but could it also be a clogged oil filter? As old brown oil was still in the oil filter when I changed oil and maybe its not mixing right. Also my moto only has 4.7miles/7.6km on the odometer, so its not old or anything
Could it also be that I didn't fill up on oil all the way? Not enough oil? Different types of oil, synthetic VS conventional mixing? Could it be that it was raining (first time riding in the rain as well), not hard, that caused the air filter to clog up?
In between oil change and from my engine acting up, I have ridden around 22miles/35km

[DrM]

I suspect you'll get  lot of feedback on your post.  My take on it:

1)  Always use full synthetic oil -- it is just better, and not that much more expensive.

2) Never over-fill your oil.  A little underfill doesn't hurt.  Oil, especially non-synthetic, will turn dark with use.  Not likely your oil filter fails, and even if it does, it is usually non catastrophic.

3) Inspect your air filter, and if it is contaminated with engine oil, then change it. If it is a K&N cleanable filter, you can clean it and reuse it.

4) Check your sparkplugs for fouling.  You can clean plugs or replace them.   

5) Unlikely your 2014 Bolt has such low mileage.  More likely the prior owner(s) had installed a KOSO meter, and then changed back to OEM meter for sale.

[joko]

I'm a little confused by a couple things. 

Your odometer only has 4.7 miles on it but you just did a 650 mile trip?

Your air filter was leaking oil?  Is it an exposed/reusable air filter and you over oiled it?  Or you had too much oil in the engine and that's where the excessive oil was coming from?

Sounds like you over filled the engine before your trip and then during your trip, you noticed oil leaking from the air filter, removed some oil from the engine, and the bike ran fine after that for the remainder of your trip?

Then after you got home, everything was still fine until you changed your oil?  Is that correct?  Or did the issue happen before you changed the oil?

Highly doubt switching from convention to full synth is going to cause sputtering, nor is mixing brands.  What's the oil level on the dipstick?  As long as it's overfilled you should be ok (and of course underfilled for that matter).

If you suspect the air filter is clogged, you could try running the bike in the garage w/ the air filter off and see if it sputters.  If no sputter then a good cleaning might be in order.

I guess bottom line:  what is the last thing that changed before you started seeing the issue?

[aussybolt]

overfilling engine oil is a  BIG nono and is not ok

[lunkhead]

If the stock paper air filter gets oil soaked, the spark plugs will foul. Even after you drain out the excess oil from the crankcase, the spark plugs would still remain fouled because of the excess fuel (lack of air). You should replace the fillter and plugs.

[DelawarePete]

I suggest you no longer work on your bike and bring it to a shop. 

[Antonio9M]

thanks guys I'll do that, 
the odometer says 4,700 miles
and the air filter is the stock one, and oil started to leak cuz I put in too much oil b4 the trip, and yup just as you described.
The oil level is fine I'm pretty sure, has 4 quarts in.
The last thing that changed, was the oil. Took old oil out and new oil in. Then took it for a wash and it started raining.
Why do you recommend to bring it to a shop?

[DrM]

thanks guys I'll do that, 
the odometer says 4,700 miles
and the air filter is the stock one, and oil started to leak cuz I put in too much oil b4 the trip, and yup just as you described.
The oil level is fine I'm pretty sure, has 4 quarts in.
The last thing that changed, was the oil. Took old oil out and new oil in. Then took it for a wash and it started raining.
Why do you recommend to bring it to a shop?

Delaware Pete is just being cantankerous.  We all start off making mistakes.  I can't even count how many parts I broke, or bolts I sheared when I started doing my own work so many decades ago.  Your doing fine, and asking the right questions.

[Antonio9M]

thanks for that kind response, and yeah never brought it into the shop, took it out for a test ride to see if it would happen again.... and nothing. Ran perfectly fine, have taken it out 2-3 times since then and nothing, so it does seem it was water/rain related. As from other ppl's comments on here and reddit, it may be electrical componets, air filter, or somehow water getting in tank, all very weird... but glad its not happening, going to replace air filter sometime soon anyways