Car doesn't want to move

Push the clutch in.
OOps sorry wrong thread lol.
Sounds like the trans is stuck in two gears.
Probably the high clutch is not releasing, and the trans at standstill is engaging the sprag. So with the hi still engaged, it is locked.
The stalls the engine part tho is a stumper, because as soon as you release the gas pedal, the TC should slip.
I'm with whoever said drop the pan and see what's in there. If clean, time for an air-pressure test. If not clean, well, Miller-Time. or in the USA I guess ;time for a Bud-Break.