Hey guys, I need some help.

I just put my engine back in after crash damage and when I went to start it, it would start but cough and sputter unless revved. I checked for vacuum leaks, found none so i swapped afm &j boot from parts car, a 84. It would fire but die. I swapped my late dme for an early one and it fired right up and runs strong.....for two minutes! After that it won't idle,it bounces from about 200 to 1,000 rpms. Again, I cannot find vacuum leaks although its possible.

My question is, since the dme controls the idle valve on late cars but I now have an early dme, is the valve just freaking out? And can I just run without the valve on a race engine?

Thanks
Ron

The two mins sounds like your O2 sensor is telling the DME you are very rich or very lean and the DME is responding by altering your mixtures to compensate (but being a bad signal is making it too rich or lean).

Unplug the idle stabilizer and o2 sensor. Get engine up to operating temps. I have had a problem in the past where it would not idle unless warmed up.