I got a 88 gxl with 76,000+miles and it had bad exhaust leak when I bought it so I replaced it and bought racing beat headers presilencer from a buddy. Now it idles way to low and it stalls out. Do I need a air flow sensor or do something with the ECU?? Before it would idle at 1500RPM then to 900RPM when it's at operating temperature now it just drops to 300-500RPM. Any ideas??

 

You have probably introduced a vacuum leak.

When you installed the headers, did you also pull the airpump and block off the ACV? If you just left the split air pipe dangling in the open I believe it will create a vacuum leak.

 

The engine will actually run just fine with the split air port open to the air w/ the ACV in place. I did it for years w/out issue. My bet would be a vacuum leak in the intake area. Check out the plastic air duct running to the TB & anything else you might have touched while installing the header.

 

+1
Did the same with my car.

 

ACV? Um I took off the actuators to remove the stock exhaust manifold and put them back on. If thats what you're talking about.

 

Air Control Valve. Acronym list is in the FAQ, as well as the Factory Service Manual.

Once the airpump is removed, the ACV must be blocked off.

 

Ok I'll check it out.

 

definitely sounds like a vacuum leak!

 

Nope I didn't touch the ACV or the air pump hose when I removed the old exhaust manifold. And I don't know if the vacuum leaking or not but I'll remove vacuum hose and check for cracks. Anything else should I check?