Cobra intake and speed density, erratic idle

[1987stangman]

Hello everyone, this is my first time posting on here. I recently bought a FRPP Cobra intake replica and installed it. I guess my first question before I get into my problem is can you use this intake with the SD system? With that said, here is my problem. Got all finished up with the install and I base timed my engine and timed it to 10 deg (for now). Car fired up ran great and I shut it off and finished re-installing all the small stuff. I got into the car and started up and it would start and die unless I mashed the gas a little and then it would idle great. This will happen EVERYTIME it was shut off and then restarted. I ended up replacing the IAC (think it was going out before hand any way). Now the car fires up and idles, but now it idles TOO high and will come down to 1k or 900RPM after sometimes 5min or sometimes imediatly, but seems to be getting worse.

I have double checked the vacuum lines
Ran a code check KOED and KOER and came up clean other the the computer reporting that the Thermactor is not working (not there anmore)

Someone was telling me that it could possibly be the ignition control modual. But I cant see why this would cause an erratic idle.

Other than this, the car runs strong and seems to have more power

Thanks in advance for the help.

S

 

[jrichker]

See "Help me create the Surging Idle Checklist" at http://forums.stangnet.com/showthread.php?t=534062
for help with your idle problems. The first post contains all the updates to the fixes. I continue to update it as more people post fixes or ask questions.