help help HELP!

[shipp13u]

1991 Cadillac sedan deville 4.9 liter,

Start vehicle, idles at 650 rpms, put vehicle in gear (any) maintains idle, push throttle, vehicles atemps to rev higher but chokes down and 855 of the time dies.

No touble codes present, unless we unplug any component and set a code.
fuel pressure is maintained in gear and at idle.

at idle vehicle goes into close loop and runs steady, but looses running ability when throttle is goosed open.

tps within specs
isc within specs
coolant sensor within specs
mat sensor within specs
map sensor within specs
crank signal detected
cam signal detected
timing 10degrees btdc @ idle
advance is working when vehicle allows you to open throttle to increase rpms
altenator 13.2 to 14.2 within specs passed altenator test
altenator eddy currents above .50 acv reading .183 acv

monitored voltage signal from pcm to sensors, pcm allows 5volts to be sent to sensors and should maintain a fixed 5 volts to 6 volts engine running or not.

Key forward 5volt reference signal
engine running observing reference signal votlage is very sporactic, from -8.volts to 20 volts. Tested a running vehicle same year reference signal is maintained throughout any engine state. replaced pcm with used computer, same results, Monitored vehicle with serpentine belt removed, altenator,Body control computer, derm module, unplug all sensors chek voltage with koeo everything has proper voltage supply, started engine with systems unpplugged, monitored engine reference ssignal sproactic from-2volts to 20volts.

stripped back engine harness for visual inspection no bad wires detected or connectors. not interested in turning over to deallership at this point,

If reference voltage is sporatic as so, why run at idle but not with load?

what can cause the high voltage spikes without the other comp0onets in the circuit?

Is there a sure test for the pcm?


Lost in the woods, testing computer to thebest of my ability.

HELP@!!

[HAWG]

have you checked to make sure the cat is not clogged? try disconnecting it and see if it will run...

[maxwedge]

Or tested fuel pressure.

[DFBonnett]

At this point, I'd check the wiring inside the distributor as well as get the ignition module itself tested.