torque coverter?

i am having a problem with my p38 which is when engine/box are warm i can put it into reverse and it selects the gear but wont rev at all and some times stalls. it also is very slow in drive sometimes when pulling away.
It sometimes wont rev when started from warm when in park or neutral.
It only does this when warm and is fine when cold. i have changed oil in box but no differance at all.
Also since this problem it is winding over alot when engine is warm and sometimes wont start at all.
could all this be connected?
i have trawled through this forum and can not find anyone with same fault can anyone help
thank you

Fuel pump or ignition amplifier would be my bet , maybe even blocked fuel filter or failing TPS as mine was recently