Weird Idle issues

Truck: 2003 Tacoma SR5 2.7 4x4 with 85k miles

Issue: After cruising on the highway for 20 minutes or so, longer also when I come to a stop my idle fluctuates from 1200-2000 up and down then stays around 1250. If I cycle the key it will continue to do this also. Then around town I have had it dip down too 548 and almost stall before i recover the idle with a rev I get some fuel knock while doing this. What would cause this...I'm new to Toyota.



Thanks for help Dave

 

bump

 

Is the check engine light on?

 

Nope

 

My 2.4L did this one time. I cruise down the interstate for about 3 hours at 80MPH, then when I get off the interstate it would idle at 2-3000RPM's. After a few trips it quit doing it. Course this happened right after it sat for 2 years, only getting driven about 1,000 miles within that 2 years.

 

Try checking your vacuum lines.

 

Ill give them a good look over

 

No leaks. All lines are intact. Even tried the propane trick.

 

This idle problem just developed recently on a 2003 model? I'll bet something came loose... +1 on the vacuum line check. Look for cracks too, not just loose or missing connections. Also check for cracked or loose wires.

Any service or repairs done recently?

 

Yes just recently but it's intermittent meaning it will happen today but may not tomorrow. Ill check for cracks and loose connections at the TPS and IAC. I hope the IAC isn't the cause because that sucker ain't cheap

 

X2 it's always something small that you can't find and it's a bitch

 

Yea I hope it's something small. I gonna look at it once this rain stops

 

Diagnosed it. Pretty obvious now. Idle dropped to 300 then it recovered about a few seconds later.threw a new OEM IAC in it PERFECT now

 

Good to hear you finally solved the problem.

 

Gosh dang it I lied its back

 

Try checking these also:
Spark plugs and wires
Air filter (also check your MAF sensor while your at it)
Fuel filter
Fuel injectors

 

Where is the fuel filter? Plugs have 3k on them. I cleaned MAF with MAF cleaner along with the throttle body.

 

Any residue on the plugs?

 

Nope

 

This same thing happened to me back several years ago. i had a 2001 2.7 single cab. I ended up cleaning the throttle body good and and the maf and it fixed my problem. but it didnt seem to help you though! not sure what it would be