Funky Idle before truck gets warm

[BRZ71]

Last week we were in the mountains and I noticed when I started my truck up in the morning that it was surging, 500 rpms then down to say 200 then back then almost like it was going to die. I thought it was the elevation (we are normally in Louisiana). Got home and all has been fine until today. On the way to work I stopped at a stop light and the same thing started happening, had good acceleration, and no stumbling except at idle. After a trip on the interstate to work once I got off the interstate no more surging at idle..... Seems to only be doing it when the truck is cold, and only at idle. In gear and out. Any suggestions??? No check engine light, and haven't tried to pull any codes yet. 2003 Z71 5.3. Hope it is not the fuel pump!

[chanswork]

Your throttle body is dirty. Just clean it with a bottle of throttle body cleaner from your local auto supply shop for $3.00.

[Bish]

Your throttle body is dirty.  Just clean it with a bottle of throttle body cleaner from your local auto supply shop for $3.00.

 

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Also, check the IAC (Idle Air Control) valve that is installed in the Throttle Body. Mine did the same symptom and when I pulled the TB to clean it, I could see tons of crud on the IAC. Cleaned it, did the idle re-learn, and it hasn't come back in 40K.

 

The idle re-learn is not critical IMO but here it is. First, disconnect battery for a few to forget. Start truck and get it to temp. Put parking brake on and pt truck in D for 5 minutes, put it in N for 5 minutes. Done.

[BRZ71]

Thanks! Will check this afternoon.

[BRZ71]

Do the 2003's have the IAC valve?