For starters my truck has been hard starting when it was cold ever since I did the TPI swap, was able to correct that problem by installing a new Holley Fuel Pump and trashing the Pulse Damper which had a rip in the bladder. I reset miminum air and readjusted the TPS and it runs better now, but still only idles at 500 rpm. When the engine is cold, it fires right up to about 1000 rpm and slowy comes down as the engine warms, but the idle always falls to 500. When the engine is warm and running, I can dissconnect the IAC Valve and nothing changes, same when I plug it back in.

Does this mean I need a new IAC Valve?? Is there a way to test these things?

 

what model TPI do you have? i.e do you have pre 1988 with the 9th (cold start) injector? And what type of air cleaner are you running?

 

It is an 89 TPI 350 (says that in my Avatar) and it is an open element air filter like a K&N.