Hey guys!
I've got an 86 SE 4spd with a 98 3.8SC from a Buick regal if I remember correctly. Finally getting back on the project and am running into some issues. Seems to idle great, and drive fairly well under 1/4 throttle. Over 1/4 throttle (especially in 3rd/4th) it will buck, thinking either lean condition or ignition loss. Also, when driving at speed, if I clutch in the motor often dies. Though this may be due to the pcm not having the VSS hooked up and trying to idle down too far, but after wiring that in (and verififying w/ OBDII), still dies. This only seems to happen in 3/4 gears. I did find that the fuel filter was fairly plugged (probably from before I cleaned the tank), so I replaced it which helped some. No codes stored on the PCM. Fuel pressure is steady at ~50 psi. I did install a higher flow pump (ep381). Figured I'd see if anyone else has run into similar issues.
Thanks,
Lukas

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4 speed 86 SE with stock 98 3800sc

PCM is programmed for a manual transmission? Yes. a no VSS signal issue would cause this problem.

Congrats on the swap. Fuel psi too high. Check specs, I'm thinking 40 psi. Check your ignition wires for proper connection to coil packs. Take pic of engine bay and post it here. Sometimes the obvious can be looking right at you.

Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

There are rare situations where the OEM idle settings do not work with proper VSS, although I've always managed to use the OEM settings. You could try to increase the throttle stop/drill a hole but you can also modify the idle follower tables to have more idle valve speed.

The rest of your issues are mechanical. Fuel pressure should be 50 all the time. The absolute most common 3800 issue is spark issues either the wiring to and from the ICM, the plug wires, plug gap, bad coils or lastly bad ICM.