My '84 gt 5.0 was only revving up to 4-5k at 3/4 throttle. More throttle, and it would drop to 3k and "hang" there. Back down to 3/4 throttle, and the revs would pick back up. Cruising down the road, it would do OK. Figured it was flooding when the secondaries opened up, so I reset the aft float. Nope. Another thing I noticed was the air pump hose was popping off. I figured it was a pump gone crazy and super leaning the mixture! The carb shop saw it all different-"The hose must be coming loose from too much back pressure." Bulls eye! Disconnected the exhaust, and the car rev's fine. DUH
johnc

 

it shouldn't have that much back pressure.... hmmmmm wierd, at least you found the problem

 

Yeah, who woulda thunk it. I think the cat might be plugging up. I have heard of that before. The cat was replaced less than a year ago, so I did not suspect it.

 

return your cat for a new one...hopefully u havea warranty since not so old?

 

Yea, that's probably it. You know you can upgrade your mid-pipe to a true dual by getting a new tranny cross-member? It's not too bad, my dad had an 85 he did it on. Then you can get any H or X pipe for the 86-93's.

 

I bought the car right after the cat went on. Dunno if there is any warranty paperwork for it.

 

Cut the cat out and leave it out if you dont have SMOG *****.

If you have pollution control hollow out the cat and use it as a resonator.

 

This is SoCal, smog ***** are alive. (some companies have installed lazer/photo scanners in the employee parking lot-they squeal on you, and get a "smog credit"). The hollow out idea might be the way to go. Then I can slap on a generic $75 cat when I sell it, and advertise "brand new catalytic conv."
johnc

 

what does this xmember look like? the one on my car has a raised section on the passenger side for the pipe to pass under. The car had a later 5 spd put in it-wonder if the xmember got swapped too.

 

here is a pic

[IMG]local://upfiles/1534/Bz767822248.jpg[/IMG]