94 chevy pu feels like its missing gas ?

[mrpike1973]

i have a 94 1/2 ton p u. 4.3 moter auto trans just bought it 256,ooo miles. when driving around 55 mph sometimes not always its like i can floor it and it just doesnt move slowly loses power then it comes back to life again and drives fine. i thought it might be the transmission but if i slow up and hit the gas again it feels like it could die. seems to idle ok. very intermittent sometimes 2-3 weeks then it will do it all the time. egr is new new plugs cap roter plug wires the only code i could get was o2 sensor rich. high miles but when it runs its excellent. fuel pump maybe? i wont put alot in this but need direction where to go thanks

[Jeremy airjer W]

What was the exact code?

If the O2 is stuck rich than it will try to lean out the air fuel mixture. I have had them go so lean they have caused a lean misfire and poor drive ability.

Do you ever notice an extended crank after a hot soak?

[mrpike1973]

not sure on the code i will have to have it read again. starts right up after running a long time. this was my nephews truck and he "accidently" forgot to tell uncle it had this problem. called him today he said his mechanic said it was timing they replaced the whole distributer. cap, roter, plugs, wires ,fuel filter, does this sound at all like a tranny? i will have to get it in the shop to have the codes read thanks o2 sounds promising

[Whoaru99]

One of the injectors on my 94, 5.7L truck went flaky that gave somewhat similar symptoms at first. Finally the injector apparently totally failed then it ran really bad across the board such that it was basically undrivable.

Had to replace the fuel pump on mine as well. No precursor symptoms to that though. Drove home from lunch one day, truck wouldn't restart after lunch, just like that it was done.

[pureinsanity]

my initial thought before reading everything was an injector.