I have a 1992 Blazer with a 350 TBI, automatic. At idle is sounds fine, going down the road on the gas seems fine. If I take off very easy it stumbles of coughs. The entire truck chugs. Some times if I let of at low speed it almost acts like it will die. Things to note, seems to idle high all the time, let off the gas and it will go 15 to 20mph with no throttle, gas millage is between 11 and 12 mpg. I just bought the truck and figured it needed a tune up so, new plugs, wires, cap,rotor, MSD coil, fuel filter and today thinking it was a fuel pressure issue I replaced and the pressure regulator. I can not find a vacuum leak any where. Oh, new 02 sensor as well.

Ideas????

 

I would check the throttle body base gasket (between the throttle body and the intake manifold). I have seen these fail and cause very similar concerns.

 

i have the same prob. but with low to normel idle. mine is a 87 350 tbi if you fig it out let me know i will do same.