I pulled a plug and seems clean. But also was burnt up. Could a bad spark plug/plugs cause a stalling issue once at operating temp? I also noticed a vacuum line has been cut, went from the bottom of the intake manifold to a sensor nearest the back of the engine bay on the passenger side.

 

This is a good place to start, replace the spark plugs , make sure to gap them to spec.
If possible try to use Motorcraft plugs.

 

thanks for your help so far, I got all new spark plugs in the car. It took a couple times cranking to get it to start (improved from 5 or 6 cranks) and it didn't die after cold start up. Warmed up to operating temp and kept running so I let it idle for another 10 minutes or so, never stalled. Finally decided to take it on a test drive so I got in, clicked into reverse and it immediately died.much improved from before the spark plugs but I guess it didn't fix the issue.

 

If the plugs made that much of a difference, it would seem the vehicle is due for some more routine maintenance among which would include the fuel filter. There should be no loose, disconnected, vacuum lines. If the vacuum diagram is still present under the hood it should help answer where the hoses go.

 

Is this the condition your describing?
it start and runs in park and neutral but stalls when you shift into any drive or reverse gear? That sounds like ttc stuck on.