hey everyone I have a 2000 s10 blazer that has a shifting problem and i have now clue what it is. Iv'e spent a few hundred already trying to get it running good, and no luck. It all started when I bought it. I bought it USED and it has a SALVAGED title. It started with a miss fire (piston #5) I replaced the Cap & Rotor, Plugs and wires. This didnt solve the problem. Longstory short, I have replaced what I just mentioned plus fuel pump, Fuel Pressure Regulator, Fuel Filter, Computer, Injector Harness wires, Air Filter, Did an Oil Change and the truck still shifts kinda rough. I was told it could be the MAF sensor, but not sure. I cleaned mine put it back on and the truck shifts GOOD but it runs kinda crappy ( it's kinda sluggish) an viseversa, if I unpug the MAF sensor, it runs GOOD but it Shifts CRAPPY. Please Tell Me Someone Has Encountered This Problem And Knows What It Is Before I Go Buying Anything Else!!!! Thanks In Advance.

 

have you checked the Tranny fluid or had a flush done?

 

No, I'm ready to give up and take it to a mechanic though. As soon as I connect the MAF sensor it shifts good but boggs, and if i dicsoconnect it, it shifts rough from first to second and if i try to pass someone up it just rev's up and wont actually shift untill i let go of the accelerator. Someone suggested it could be the throttle possition sensor coul that be it??? Well now that I think of it, I did check the fluid and it was at the right level, I have not had it flushed.

 

The 2 main things that come to mind for me are the Fuel Filter and Throttle Position Sensor - If I were you I'd change both. Cheap fix if so.
Either that or hook a scan tool or multimeter and check the fuel filter before buying another.