I've been having 4L60E issues with my truck. A previous owner stripped out one of the pan bolts and fixed with a helicoil. Would a leaking transmission pan affect the fluid pressure and shifting, or maybe cause the TCC to stick? Thanks!

 

It would be a problem only if the fluid level went too low. The heli coil is a common way of repairing stripped threads.

 

Take bolt gently out.
Clean threads in both places with brake cleaner
Put red Loktite onto the bolt threads
Apply one layer of plumber tape to the bolt.
Gently put bolt back in and do NOT overtorque.
Out of some 12 bolts, one does not do much difference. But it may leak around the bolt, hence the above.