This is 95camaro 3.4 v6. With 66000 miles on it. When I put it up for the winter it ran great. Just needed cat converter. Got it out this spring. Idles great. Runs rough when driving with weird noises in back. I've replaced cat converter, upper and lower intake manifold gaskets, plugs, wires,throttle body gasket,valve cover gaskets. Still drive terrible. I'm at my wits end with this thing. I've been trying to fix this thing since February and it still isn't right. Anyone got any ideas. thanks.

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Is the check engine light on? How are you deciding what to change? Most of the gaskets you replaced would cause a rough idle but it would drive 95%.

There are still dozens of things that can cause rough running under load. Timing issue, Fuel flow or weak spark. Also the are EFI sensors that can cause it.

 

No, The air pump is an exhaust only emission item that will have no effect on how the car runs. Are you reading the correct manual for tests? You jump the wrong wires you burn up a lot of money.

There is a very straight line to figure this issue out, you may not have the right equipment but if you answer my questions I may be able to help. If you are just going to do random stuff that makes no sense you will do more harm then good. You really want to keep how much you mess with a 24 year old wiring harness to a minimal.

Is the check engine or any light on in the dash?

If you really want to run tests, then test for weak spark on all 6 cylinders, fuel pressure test while the car is running and missing.

Things like O2 sensor should be tested through a PCM scanner. If you start disconnecting stuff before you scan for codes you make this 10 times harder to fix because you will set a bunch of error codes and we will have no idea which ones are the cause and which ones you caused.

 

double check that the plug wires are in the right place. easy to get wrong. sometimes a switched plug wire can idle ok but not perform.

 

no no dash lights on. Everything I've done is what was recomended to me from another website. That's why I came to this website.

 

Without any equipment you may want to try read the plugs. That is when you pull the plugs to see if the any of them will show indications of what going on.

Maybe a video of the engine running badly?

Common issues for your described condition.

Spark: Weak Coil, ICM, cracked plug (common defect on new plugs)
You can check for weak spark with a inline spark tester.
https://www.harborfreight.com/90-in-...ker-69023.html
You hook this inline with the plug and just watch the light. The light should stay smooth and consistant on all 6 cylinders.


Low Fuel pressure. Pump has low volume issue, Pressure will show fine with the motor off or at idle but one the engine needs more fuel the pressure will drop and starve the engine. You said you did a fuel pressure test you just need to do one with the car is running bad.

Timing chain jump. An engine that a slipped one tooth on the timing change tend to idle great but they have no power and will miss. Vacuum gages is the best way to detect this.

Fuel control issue. The hardest thing to test without a scan tool. Is there something wrong with the fuel injection that is not thronging a code. Does the Service engine light/check engine light come one with the key on before the engine starts?

 

Car fixed. Thanks.

 

come on now,,, what was it... inquiring minds want to know...