Random RPM drop, shake vibration while idle

My 2.4 Tacoma has developed a random rpm from 680ish in gear at idle to 584! drop while I’m at the stop light it doesn’t do it all the time as I thought maybe my brake booster was the culprit , new plugs ,cleaned intake throttle months ago including the iac valve with new gasket, checked my LRFT and it’s on spec according to the Toyota manual so no leaks , your thoughts

 

Have you checked the TPS, with a volt meter, to see if it’s within spec?

 

This might help...

 

No I have not ,will be my next step at sunrise

wow thanks man ! I’m actually looking into a a bad tps sesnsor since most of the symptoms are there

 

I have seen that some TPS sensors don’t have an adjustment, so this schematic might not apply. I would definitely look into this though. Good luck!

 

See if the defroster is on. May be the AC compressor coming on.

 

Posted a year ago, I know, but my idle was high for the longest time. I replaced the TPS and IAC, to no avail. A problem existed in the throttle body it self. The brass butterfly valve became oval over time and created a huge gap. This gap was allowing more air to pass in between the valve and the shaft, causing a higher idle. I sent my throttle body to maxbore.com. They did a fantastic job! I was able to adjust my idle to factory standards.