engine runnin rough/no power on take off

[piercedjoker72]

i have an 88 gmc jimmy full size 4x4 5.7 350. it started runnin rough, i went by the book, new plugs, wires, cap, rotor, injectors, tb gasket kit, pump 4 mos. old.

set timing, got it to fire up, have high idle, loud air hissing around tb and when i try to drive starts bogging down, backfiring and has no power? HELP

[Matt99Z71]

Vaccum leak? Look around closer. Maybe a rubber hose split.

[Cool Zr2]

Egr valve, check that.

[piercedjoker72]

thanks both of ya, i'll check, i also heard of checking the base of the throttle body for vaccum leaks with water, any idea how this is done

[Butch 02 Denali]

Just pick up another throttle body base gasket and pull the TB, I'll bet the gasket is split. Common problem.

To check it, spray water around the base while its running. I use a window cleaner spray bottle. You will hear the engine change when you spray if it's leaking.

 

Butch 02 Sierra Denali

[piercedjoker72]

well i gave up. i put it in the shop and come to find out it was a blown head gasket. now i get to do a top end re-build. yay. well at least i know the prob, thanks for everyones help.