1990 Lincoln Town Car Trans or Eng issue?

Sorry I should be more clear. The engine will try to start in park, but won't run/idle in park.
The fluid is not coffee dark, maybe a better description would be a dark tea color.

Still working on gathering parts to do as you recommended. I have more information. With key on I receive the following error codes:
14, pip circuit failure
34, no egr flow
96, fuel pump secondary circuit failure

When vehicle is running the following error codes:
21, ect out of range
23, tsp out of range

Hello again,
Spent yesterday performing the tasks in the link you sent me. During those tasks I noticed that a cable going from transmission to throttle body linkage was not connected, grommet had broken and cable was just floating around. I don’t know what this cable does, can't find it in the Haynes manual. I did replace that grommet during re-assembly. I did not notice any excessive crud or blockages during the cleaning task, actually I was surprised to see how clean in was for 70k miles.

Next I checked throttle position sensor, good to go. Voltage increases and returns smoothly.

Checked idle air control, good to go. Correct ohms.

Performed fuel pressure test with kit rented from auto zone, passed.

To do:
Check coolant temp sensor / RR if required.
Check EGR sensor / RR if required.
Check pin 22 (I don’t know where this is at) for power from PCM.

Current status:
Will crank and try to start in Park, will not idle.
Will start and idle in neutral. Engine will rev without hesitation when the accelerator is pressed. --- New development --- car wants to move fwd in neutral, not much, but it will roll fwd without application of brake.
Will idle when shifted to Drive. Release brake and car will begin to move fwd, however when applying throttle, the engine does not respond, even if floored. This is very confusing to me as it will rev immediately, no hesitation, when transmission is in Neutral.

Any new ideas? Again, thank you for your time.

Forgot to mention. This vacuum hose here is very deteriorated.
While car was idling in Neutral I touched all lines and this one modified the idle range. When hose is pulled off, car immediately dies. What is this hose/sensor? I tried to track it, but it goes underneath the intake manifold and isn’t accessible. Ugh.

When I get off work I will check out the MAP for vacuum leaks.

Any hints on tracking the map hose? It routes from fire wall to center of intake. Very limited space, cant reach or even see where connection is. In your opinion, will the intake manifold need to be removed to gain access? It looks like it will.

I will check ohm's at coolant temp switch as well.

I can't believe the schematic you provided isn’t in the manual I bought.

As always thank you so much for the help you have/are providing! Will be sure to follow up this evening!

Coolant temperature sensor checked good.