I also have a 1.9 JTDM wagon with the same problem.
I've already scoured every other forum, pulled my car half way apart and put it back together.
Cleaned the intake, changed transmission fluid, ran active diagnostics & removed & tested the solenoid body, they are all working, so I returned them to improve reverse & forward engagement by adjusting the solenoid adjustment screws which has helped with shift timing.
But I still have the same problem with it almost stalling when I put it in drive or reverse.
Also, the throttle seems not to respond, so reving the engine before dropping it into fear doesn't really do anything, it just drops the revs right down to 700rpm again and crawls off the line.
I am pretty much at the point of dropping the gearbox and tearing it down expecting to find a jammed clutch, torque converter or one way fly wheel in pieces.
Any ideas or if you have solved this would be really appreciated. Thanks in advance.