FX Wildcat mk2 questions.

I am frustrated with my Wildcat. I have installed a power plenum, Huma regulator set at 150, dual transfer port, high flow pellet probe, and slugliner. I can not get the probe and transfer port to stay lined up. I adjust the probe to push the pellet in as far as it can go. A 34 grain pellet goes about 920 fps but after 3 shots it falls off to 600 or so. I then find the probe is needing to be adjusted again. I have installed new screws to secure things better but it still slips out of alignment. As I said I am frustrated! Help!