1998 p38 at 2000 rpm's it bucks wont go over 30 miles an hour.swapped air mass,coils r/r spark plugs fuel filter fuel pressure at 35psi.

Question edited for clarity.
Question moved to make and model category.

That is a lot of guessed parts!

Clean the Throttle Body and MAF.

Problems with the o2 sensors or the Catalytic Converter would trigger the Engine Malfunction Light to come on, as would many of the parts you swapped out. Diagnose and then fix. Find an auto electrician with a pro grade scan tool computer. That can diagnose the fault and be recorded as it is happening on a drive.

https://www.google.com/search?q=auto+electrician+near+me

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• Check your timing also spark plug wires and coil timing may have jumped

Plug in diagnostic computer for trouble codes if any.
Check condition of air filter, fuel filter and spark plugs and leads.

Aside from those listed above, other common causes of poor idle or stalling can include the manifold pressure sensor and especially the MAF (mass Air Flow sensor.)

First spray starting fluid in the air filter. If it starts it is a fuel problem. If it doesn't start then pull one of the spark plugs and see if there is spark. If there is not spark then it is an ignition problem.
If it is a fuel problem and the fuel pump is running when you turn the key on, then check fuel pressure. It should be over 35psi.
If it an ignition problem start by checking fire at coil.

Hello! A cylinder misfire can be something as trivial as needing new spark plug wires, to having a dangerous lean condition in the fuel mixture. Assuming that you have a stock, un-modified car, with a stock, un-modified PCM, my suggestion would be to swap the coil packs, to isolate whether or not the 1 - 4 coil pack is faulty.


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ck the map sensor

Could be, but more likely to be fuel. Why do I think that? Carbon build up typically happens when plugs are working (no carbon without fire) but fuel mixture is wrong (air or fuel). If coil, most likely would misfire at all engine RPM, not just low RPM. So, I reckon to look at fuel rail pressure to the injectors first - get a pressure gauge on the fuel rail and check it out. I think, but can't remember for sure, that there is a fuel pressure regulator per bank, but I could be completely wrong. But either way, I'd check that out as it is simple and if it is OK, then check out air path to that bank and any vacuum/air take offs specifically to that bank. If all OK, then why not swap coils? See if problem swaps over. If so, you know it is the coil.

This could be many things. First, start with a tune up (plugs, wires, air filter, fuel filter). Another possiblity could be your fuel injectors or bad gasoline. You could try adding octane boost and fuel injector cleaner to your gas. If all else fail it's possible it could be your coil or a malfunctioning sensor.

Hi! You must be frustrated by now! your code is marking that the O2 sensor is bad in bank 1. Did you replace the O2 sensor that is located  before the catalytic converter?  The S10 has an O2 sensor specially made for that cat. its about 30$ That would explain for your blackened spark plugs; your pc on the car is asking for more fuel. GOOD LUCK!!

can be a mass air flow, idle air flow ,or even a hole in the tube between the airbox and the throttlebody........any air leak will cause this to happen.make sure you have no vaccuume lines off either