ok here is the deal. i walk out to my truck in the morning, start it up to let it warm up, and light up a cigarette to kill the few minutes its going to take. Well about 30 seconds after i start it, my truck starts to idle very sporadically going from 1000 rpm to 300 to 500 to 1200 to 200 and so on. so i shut it off in a hurry, let it sit for a second and start it back up. When i start it back up it runs normal and doesn't happen for the rest of the day. Now i have been having problems with my truck knocking for a while now and cant get it to go away. i have changed plugs, wire, fuel filter, air filter, sprayed MAS with MAS cleaner, and ran countless cans of sea foam through it. I was told the idle is the truck going from a closed to open loop or something like that and the weird idle means a sensor is failing. i also am a student and dont have money to throw at the problem. thanks so much for any input.

 

I Had A Simular Proble With Wy Suburban And I Beleive The Code Showed The Map Sensor... My Truck Will Idle Very Poorly When Starting Up Sometime Mostly When A Cold Startup, It Continue To Get Worse Untill I Change The Map Sensor And It Went A Way... I Put The Peddle To The Metal While In Idle And It Worked Sometime Untill It Was Fixed... I Have Heared You Can Clean The Map Sensor And It Mite Work... Have Auto Zone Check It And You Will Not Have To Guess At It... I Use My Diablo To Read The Code But Do Not Remember What Was The Code...
Hope It Will Help...

 

make sure the MAF is clean, first and try it again...

 

i did and it didnt help. whats a MAF cost?

 

The Manifold Absoulte Pressure Sensor is kind of pricy, I think they are almost $60 new. I found one for $20 on egay.

 

a "new" MAF from O'riley's cost me about 80 i think. and ya the MAP is pretty pricey as well. i thinki paid 60 or so for mine

 

When you first start a cold truck, the computer does not reference the MAF or the O2s. I would start by pulling the throttle body and cleaning it out. Remove the IAC and clean it as well.

Need more info on the truck, what year, engine, mods etc