first off, the list -

355 TPI, vortec heads w/ bowl job, slight exhaust work
305 TPI cam(1.6 roller rockers), computer, injectors(19lb)
slightly ported base, fully ported plenum
SLP style TB to MAF hose, tube to K&N
shorty headers, 2.5 mandrel exhaust, hooker mufflers
stock 305 MAF PROM

Everything seems to be good now except for the idle. I've set minimum air(@500 rpm) in gear with IAC closed and disconnected, set TPS to .54 every time. - When it fires it idles up to around 12-1500 waits a about 30-45 sec, then drops back to around 1000. - In gear is at around 800. If you take off driving and just lift off the gas, it will idle at around 1300. If you tap the gas once, it will fall off to around 800. The butterflies return everytime, but you have to tap it once to get the rpm to drop down. The TPS is new and shows smooth voltage from idle through full throttle. No codes in the ecu. I' even tried setting the idle in neutral instead of drive, which got it down the the RPM's previously mentioned. It was higher when I set it in gear. what gives? I know the stock prom isn't optimum, but I've seen much more modified systems running on the stock prom. I'm staying simple because the set-up is for fuel economy/decent power.

any ideas?

thanks, justin...

 

clean your IAC

 

The IAC passage is clean. Had the TB completely apart. This is a fresh motor. - The intake passage is also clean. - I had the intake bead blasted. - could it be a bad IAC? It seems like it works, but not properly.

 

It finally dropped to 550ish(want around 700) today after being driven a little while(all new) - But still have to tap the throttle to get it to fall off. - It also threw a code 24(VSS) I'll have to trace that down. Could the ECU being unable to read the vss cause it to high idle when you slow down? - If it would fall off all the time I could reset the minimum air and tps(to achieve aprrox 700 idle rpm) and get this thing running right...

later, justin...