Stumbling when reving from idle

[Divied245]

This is long and painful post but, I just want to include all the info to hopefully find the solution.



I just did a low budget engine swap 3.9 from a 89 (i'll call it the new engine) into a 91 GDE (old engine). Old eninge was just... old and tied. new one only had 80k on it. I had put the new engine in with preaty much all of the old accesseries. It started with what sound like a lifter tick or rod knock. I ended up swapping the new dizzy on the engine and the knock went away (old dizzy rotor return spring was broke). Now the engine idles ok (slightly varies between 600-700 Rpm. I assume its normal for the age and technology). The problem is now that when you go to rev the engine from and idle, it studders and stumbles kinda like the timing is advancing. I checked the vacuum advance and it is working. Checked the vacuum port for the dizzy (before throttle plate) and its pulling up to about 14-16 Hg under throttle. Engine vaccum (after the throttle plate) is pulling steady between 17-19 Hg (varies with RPMs). Timing is set at about 8*. It just wouldn't run as good at the suggest 6*.

Because this was an engine swap i have carefully cleaned all of the following parts and have tried two of each (one from new and one from old engine, which both were running/driving engines)

-Distributor

-TPS

-IAC

-MAF

-Cap, rotor, wires, coil - both a brand new set and the old set. (new set is all lucas original. Old set is factory expect for the wires)



also tired a new fuel temp sensor, fuel filter and water temp sensor (the ECU sensor, not the one for the gauge.)



The truck also starts a little hard when its warmed up, kinda like its flooded out. If you put the gas to the floor and start it, it'll chug a little to get it going but once it gets past that, it idles fine.



During the summer, on really hot days the old engine would start in a simlar way. If i let it sit in the heat for about 15 after running, it would start hard like that. Thats when the temps sensors were replace and it helped that problem.



But, for not it still stubles when trying to rev like its either not firing or starving or something. My next guess would be injectors or a fuel pump. I have heard that you can use chevy 5.0L TPI injectors and a chevy fuel pump (not sure which one) any truth to that?



Just looking for suggestions.



Thanks guys and gals.