Under load, mostly anywhere after 2000 rpm, my car runs pretty rough. Jerks every couple of seconds, tach bounces up and down about 200rpm. Only thing changed in the past 400 miles has been oil (conventional switched to synthetic). Last 1000 miles, have changed alternator with a remanufactured one (that I found at pick-n-pull) and my TPS. I could really use some advice on this, as it is my daily driver. No check engine light or codes. Car has. 133K on it, but the engine is not really clean. I noticed a jerk a couple of times since the oil change. Drove to school today with no problem, four hours later and after it warmed up, jerked all the way home. Thank you for any support. Mostly a noob

 

Could be a weak fuel system that isn't keeping up with the demand under load, or a weak ignition system that can't jump the gap under load.

If possible, get a fuel pressure gauge on it and observe it when the stumbling happens. If fuel pressure is steady, then go after the ignition.

If fuel pressure drops, fuel filter, fuel pump are most likely.

 

Thank you for the insight. Will check when i get the chance but I feel like it is safe to assume fuel pressure is the culprit as the cap, rotor, wires and plugs were changed a few thousand miles ago, and when I take the gas cap off to fill the tank it doesn't really vent a lot of pressure (assuming that is what the hissing indicates). Assuming it is the fuel pressure, how likely is it that it could be a leak in the actual fuel lines instead of a problem with the fuel pump and filter?
After a couple days of driving it, I have noticed that the longer the trip, the worse it misses. Filled my tank yesterday and it was running pretty well, not sure if that means anything towards the fuel pressure theory. Thank you again for the help

 

Make sure one of the wires hasn't burned through on the exhaust manifold or headers.

 

That would have been ideal, but not the case unfortunately. Seems like the ignition system is alright. Car had a hard time starting yesterday. Took a few turns of the key. I understand that to be a symptom of a bad fuel pump. I'm going to assume that is it. Still going to test the fuel pressure (tomorrow?) though. What kind of job is it to replace?

 

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Fuel filter changed, changed spark plugs (to make sure), checked all vacuum lines, and still misfiring occasionally, but pretty much the only symptoms are when warm. Also, tach bounces even when not misfiring, and sometimes-even when in 5th gear-when it misses the "shift up" light comes on for half a second. I want to test the fuel pressure, however, from what I have seen, a special adapter may be needed to test the pressure so I don't exactly know where to go there. However, the fuel pump does whine for a few seconds when car is "on", so I am thinking (hoping) that is good
Is there any way the code 32 (egr code) could cause the misfiring? It doesn't move when I press on the throttle, but I am not sure if these kind of EGR's do that (the one with the three "towers" and connector together). I plan to replace the connector, as it looks kind of mangled. But could a malfunctioning EGR valve cause these problems? I replaced my EGR four months ago because I got a code 32, went to clean the old one and I kind of caused it to fall apart.

 

Ordered a fuel pressure gauge, so I should have that at my disposal soon. However, I disconnected my egr connector and the engine had no change. I assume this is a bad thing, correct?

 

Also, connected a used ECM I picked up for a few bucks at a junk yard, got a code 43, but only get a code 32 on the other ECM. Likely Correlation?