Okay so here is the deal, I cracked the head on my 2000 Blazer 4.3L V6. I got that replaced and now I have quite a few issues. First the idle was at 1,000 RPM and they adjusted it, now its at around 650 which shouldn't it be around 700-750? It jerks hard when you put it into gear and the gas pedal is stuck in place I have to literately hit it to get it free with my foot then it works right until I shut the truck off then back on then it does it again. Also when it's cold it doesn't want to change gears into 2nd, when it's warm no problem. When I'm going down the road at 50 mph its running at almost 2,000 rpm when before it ran at like 1,200 at 50 mph, even at 70 mph it wouldn't even hit 2,000 rpm, now it hits 2,000 at 50 mph. Also my heat doesn't work unless it's on the highest temp (82) and it's warm not hot like before. If I move the dial just down one notch it blows cold air. The engine light is now on and I went and had it checked at Autozone and it pulled up 6 codes (P0300-Multiple Cylinder Misfire Detected, P0101-MAF Sensor Performance, P0106-MAP Sensor Performance, P0108-MAP Sensor Circuit High Voltage, P0121-TP Sensor Performance, P0122-TP Sensor Circuit Low Voltage). All of this was fine before the head cracked. Now all this is going wrong and I have no clue what to do. If my truck is warm it runs fine. If it's cold the only issue I have is the jerking when going into gear from park and the trouble shifting into 2nd. Also my gas mileage has went down about 7 MPG. Any help would be greatly helpful. I still owe $2,600 on this truck and as of right now I don't know if I should just walk away from it or not.

 

daaaaaaang. sounds like a bad shop. i edited your story with some tips etc.

 

X2 on a bad shop, unless you did the work yourself. No way just swapping out a head would cause all your problems unless whoever did it was extremely sloppy.

 

The dealership I bought the truck from had it done and my coolant level is fine, they told me that they also flushed and filled all the fluids. The heat only works when you have the temp on 82, anything below that blows cold.

 

Idle speed should be 650rpm at operating temp, all accessories off, trans in neutral or park, all monitors complete, no DTC's in memory, no check engine light. Couple of stickers under the hood say, "Idle speed is not adjustable". What it should say is, "Don't mess with it". It is set at the factory and there are no instructions in the factory shop manual that explain how to adjust it.

As for all of your DTC's: Clear all of the memories and perform the General Motors Driving Cycle then retrieve any DTC's and post them here. Each step of the drive cycle must be done exactly as written. The steps do NOT need to be done in any particular order, but they all must be done.