Thank you Captain, I really appreciate it.
I went out this morning and took the voltage readings again.
While working the throttle by hand, and trying to take pictures of the meters at the same time, here is what I came up with: (Throughout the test, the 5v ref. at the TPS was a constant 5.01v.)
Here is the setup I was using:



Key on, engine off, TPS voltage displayed by the scan tool is 0.43, while the DMM displayed 0.538.
Tracking the voltage with the engine off, both the scan tool and volt meter display a smooth increase and decrease through the full range of travel.
Key on, engine running was as follows:
@ 889rpm (I had to shim the throttle stop to get it to idle), the TPS voltage displayed by the scan tool dropped to 0.18, while the DMM displayed 0.541
@ 904rpm, the scan tool voltage dropped to 0.06, while the DMM displayed 0.544.....
@ 938rpm, the scan tool voltage dropped to 0.00!!, while the DMM displayed 0.541.....
@ 1155rpm, the scan tool voltage was 0.35, while the DMM displayed 0.658.....
@ 1902rpm, the scan tool voltage dropped to 0.31, while the DMM displayed 0.760.....
@ 2496rpm, the scan tool voltage was 0.49, while the DMM displayed 0.890.....

It's hard for me to get my head around some of this stuff, but it really seems to me like the VCM (or is it PCM?), is acting up.
If I had an analog volt meter it would probably be easier to track the voltage, but my old Simpson 260 needs a tune-up, so I'm stuck with digital.
So, what do you think?
(I took several pictures of the scan tool and meters side by side...I can post them if it'll help any.)

 

The TPS ain't doin' squat! One more test... key on, engine off, what is TPS voltage at WOT?

 

What Hook said! That's the best troubleshoot system since sliced bread {?!}.
Wiggle the PCM harness connectors while watching the tps readout at WOT.

I've been paying attention to PCM fails since I've been on car forums.. hardly EVER! Almost ALWAYS wiring/connectors

Worst common fail PCM's I've seen are 94-95 OBDII ford injector driver transistors shorting. That was the Modular 4.6L first issue so they cut some corners to make up for higher processor costs.

 

Probably don't even have to do the wiggle test. The PCM is seeing TPS, the problem is TPS voltage isn't changing when the throttle moves. That's why it's setting the low voltage DTC. The PCM sees RPM change but TPS is indicating the engine is at idle. Either a bad TPS or the "blades" aren't engaged properly with the throttle shaft.

 

How can it track okay engine off.. bad engine running? Like something is swamping it.

 

Key ON, engine OFF (KOEO <<< Ford terminology) you can go to WOT (Wide Open Throttle) and watch TPS for drop outs. The highest reading the OP got was .890 which is essentially idle. At WOT TPS should be very close to vref, (5VDC).

 

Heh.. what I get for 'assuming'!
Get that Red? Did it go to near 5v engine off?

 

After you fix the problem, don't forget that you had gasoline in the oil. The intake manifold has two parts. the top has that plastic assembly you can't miss seeing and the bottom section is aluminum and bolts to the heads. I mention the heads because you have two intake manifold gaskets there and it is possible that the leaking gasoline is mixing with the oil via the gaskets or the injector/s may be flooding the pistons and from there the excess gasoline sips down the piston bores to the oil pan. So, change the OIL and OIL FILTER when you fix the leaking fuel issue or risk having your engine seize later.

 

Thanks again Capt. I'll redo the tests again today, both KOEO and KOER, and I'll lock the throttle wide open during KOEO and redo the wiggle test to verify.
The readings I posted look odd, but during KOEO, they look fine.
Although the .890v is low for that rpm, it didn't take much throttle movement to get there, so I was "assuming" the reading may be correct on the DMM.
The mystery to me is the scantool dropping to 0v while the DMM reads considerably higher volts, leading me to blame the VCM, (probably falsely).

Thanks pettyfog. Yeah as I recall it did.
Like I said, I'm gonna redo it all today and post back exactly what I find.
I'm not exactly new to shade tree mechanical work, nor am I new to the interesting world of EFI, but this scan tool and me need to spent a lot of quality time together, because the more I try to use it, the more I realize how little I understand about it.
It sure isn't a case of "plug it in and it'll tell you what's wrong", that's for sure.

Thanks for the tip.
I have already changed the oil and filter, before I started the engine after the work was performed. (I replaced the lower intake gaskets and the fuel injector spider assembly.)

I want to thank all of you guys for helping out with this issue, and as aggravating as this has been, I feel like I'm learning a lot of important stuff here, so it will not be in vain.
With the info I'm gathering here, I'm fully confident that I will get this truck back on the road.

 

I have a PCM for a '96 that I bought several years ago (used) that I was hoping to use in my '95....but of course I could not.
It is of no use to me and has been gathering dust sitting on a shelf.

Any interest in this for the cost of shipping?
I will find it and get the part number off the top of it if you are.

Later,
LannyL81