OK, I figure its time for an update. I replaced the intake manifold gaskets, which helped, but not completely fixed the problem. I think it was a combination of problems, the next of which is a throttle cable issue. It sometimes sticks at 1500rpm, but drops to 800-900 when I blip the throttle. I already lubed all I could access, so I'll see what I can do this weekend on that.

Also, something which may have contributed was a HUGE exhaust leak. The exhaust manifold-to-head bolts were VERY loose, and 3 were completely backed off (the head was 1/4" away from the manifold, not even touching). I torqued these down, and the car sounds much smoother now, and seems to run less rich.

However, I think I have an oil leak as well now. I will occasionally smell the stench of burning oil when stopped. I changed the oil when I replaced the intake manifold gaskets, so it's possible that I messed them up, or the oil filter isn't on tight enough. I'm going home again this weekend to lower the car and install new brake pads, so I will look into this a little bit.

I think some of this may have gotten over my head though, as I don't just want to throw money and time at it. I live 30 minutes away from Tony's Corvette Shop in Gaithersburg, MD, which is well known for its quality work. I may just take it there next weekend or so to have them look at the problem.

I guess I'll give another update when there's something to update about!

 

Was this ever solved? My '96 LT4 is throwing a P0507.