Guy's, I am a first timer here. I have an 89 IROC/Z with 350 TPI 5.7L, and am having trouble. While driving at speeds of 35-50 mph, my car surges, but if I let go of the gas or give it gas it stops surging. I don't know if it has to do with the fuel system or the transmission. Also, it seems like when the car has been driven for a while it starts to make a loud whistling sound coming from the gas tank. What can that be? I've taken it to the shop for diagnostics test but they say the fuel pump and fuel pressure regulator are fine.

 

Welcome to TGO!!
Hows the condition of your cat ? "when you tap or shake it does it rattle?"
How old is the ignition system IE coil, dizzy, wires, plugs
Is timing set correctly?
Have you checked for vacuum leaks with carb fluid ?
You pulling any codes ?

 

You can try to look at the EGR. That could cause those same issues

 

Have not checked any of those, but I will tomorrow. Thanx for the info.

 

My car was surging or hunting when i was goin those speeds also. mine turned out to be the tranni it was low on fluid thank god i figured out what it was before i had a major tranni screw up or something. anyway i hope that is of help