[truktruk]

Bought a basket case of a 94 2500 Suburban a while back with a 350 TBI/4L80E and ended up rebuilding the top end due to bad valve seals (exhaust was quite smokey) Another problem it had prior to the rebuild was going form Park to Drive/Reverse, the engine would bog down and die. It still does this after the rebuild and Im at wits end trying to find the cause. Thing ive done/noticed:

-Entire new top end/Distributor/coil/plugs and wires
-New fuel pump/lines/filter/
-Rebuilt throttle body
-Base timing is at 0 with advance unplugged
-Aside from the EGR solenoid and knock sensor, all others sensors are new
-replaced both VSS in the 4l80e trans (atlhough only the one closests to the engine is the only one hooked up, understand 4wd models dont need both VSS in the trans connected?)
-New Hydroboost unit
-When i do Fire it up, it will roar to life most times and hunt for idle for a second or two
-When it warms up a bit I can shift into D or R all day and it wont die (sometimes it will though)
-SOMETIMES when I press the brake pedal at idle will will bog the motor down to almost dying (has hydroboost)

I feel like ive done all the troubleshooting to my knowledge level and still cant say if its a engine or tans problem. Hoping someone can point me in a good direction

 

[truktruk]

Another noteworthy tidbit:
From a stop, if i ease into the throttle it will not accelerate for a moment then the power/forward movement happens. If i get on it a bit the acceleration is instant.

 

[JackE]

Have you done anything with the Idle Air Control Valve? With everything else you have done, I would be taking a look at that component.