I have a '94 5.0 5spd. While out cruising at 75mph (Legal) there was a sudden change in the exhaust note and now it runs like it has a sock stuffed in it.Tuned it up, change pvc and fuel filter. Still not right, any advice.
Not the car in the picture.

 

Sounds like a sock got stuffed in it, ya ask me...

Ok, seriousness, but it acutally sort of sounds like that might have happened... in the form of the catalytic converter substrate. If your car is running rich, then the extra gas in the exhaust will burn there, and that extra heat will melt/destroy the insides of the cats.

Happened to me too. No real warning, it just... happened. Fun time. '97 HoopTBird. No engine lights, no bad running, just... done.

Of course, the reason was two months previous I had leaky injectors what were causing issues of running, which I finally did fix after chasing the issue. **** thing was intermittent. But by then the damage was done, it was a matter of time... and then boom, new catalytic converters were needed. Yay.

If it's not this in your case, fantastic. I really hope it's not. But I think it's probable, given the description...

Hope that helps in any event.

 

No cats. done nothing with injectors.

 

Well, in that case...

I got nuthin'. You probably need a good diagnostic shop to deal with if you're modded up. Perhaps going back to stock is the answer. I don't know, man, mods screw up diagnosis like that.

If the cats are the only 'mod' you got, the assumption has to also be that you have HEGO deletes and there's been threads regarding those things. Otherwise, it's fuel, exhaust in general, spark, computer, engine itself.

Good luck, I hope it's not expensive and you figure it out quickly.

 

I would,at minimum,run codes & a compression test.The cel/mil doesnt have to be lit up,on a 94-95 model,in order for codes to be present.You don't need a scanner either.Just a jumper wire/paperclip and your cel/mil to use to count the flashes.The following link will explain how its done.Post any codes you get (if any) You should at least get code 111 (system passed code) even if no other codes are present.

http://www.amopower.com/eec-iv.htm


After that,I would run a compression test to see if any cylinders are down lower than the others.Make sure the engine is at operating temp and the throttle blade is held fully open during the test.

Another possibility as far as the exhaust is concerned are the mufflers.They can collapse internally,depending on what brand/
style you use.Some dont really have much inside them to collapse while others do.Can you feel a drastic difference in exhaust flow coming out of one tailpipe vs the other??