idle RPM fluctuation

I have a 2001 tacoma sr5 4X4 that has a 3.4 liter V6 from a 2004. Ever since we swapped the motor, the idle will sometimes run at like 1500rpms for several minutes (like 10 or more) after starting. Or sometimes after starting it runs so low that you have to give it gas for awhile to keep it running. Today it wouldnt start at all without feathering the gas pedal. Where should I look? Thank you for any advice..

 

Try cleaning the mass air flow sensor and the o2 sensors with some contact cleaner, and maybe try pulling the EFI fuse. Disconnect the battery and reset the computer. Maybe it needs to have the comp reset. How long has it been since the swap? (miles)?

 

Ok thank you so much, I will do these things along with checking the AIC. There are about 15k on it since the swap. Most of the time it idles just fine after warming up, but it almost always needs a little gas at first to warm up and run on its ownn..

 

X2. You can try and clean it w/ some contact cleaner, but usually if its bad, it needs replaced.

The way you test it is to take the valve off the TB (throttle body), keep it plugged into the wiring harness and turn the key on (dont start it) and see if the little valve moves inside the IAC. If it does, its good. If not, its toast.

I would also clean the MAF and the TB to see if that helps.

 

Thanks so much for the info and speedy responses!

 

I'll throw in my standard response (based on my experience)

My throttle position sensor was shot and it would idle high, it would idle low... etc

 

Bit of a thread jack...

Mine started idling between 500 and 750 on Friday. A bit annoying, but it accelerates smoothly, any ideas?

 

read just about every post above yours.

 

I was afraid that would be the answer...

Oh well, search for the write ups, here we go...

 

subbed.. my idle also surges from about 900 - 1100 rpm upon start-up, but typically levels out to around 750 after she's warmed up.. truck runs perfect otherwise

I'l look into all the above, thanks