thestumper,
I guess what we could do when purchasing a P3 engine, is go to the store, and have the exact engine we want tested on their tracks, using a Z4K transformer with side receiver, and DCS hand held remote control, have the start up in all the different run options tested, including the TR TIU mode. If the P3 engine works properly in all the different modes, that is the engine you purchase. Got a hunch after the 1st couple engine with problems however, the store owner is not going to want to test the P3 engines any more. I still believe this is a P3 quality control issue of some kind.
PCRR/Dave