transmission slippin? problems? AHHHHH

The Ride: 01 prerunner v6 automatic tranny ext cab (NO 4x4) 155k miles on it

The Problem: I bought the truck back in January this year, about 3 months ago i noticed the truck doesnt click in gear as well for reverse. Like it will naturally go backwords but when you accelerate it slips. Then, this last weekend it did it in drive. I went to accelerate and it jus rev'd up the rpms as if it was in neutral. I stop the truck put it in park then back in drive and all was fine, which hasnt happened again in drive. But now that i think about it, the truck has seem to have died down on the acceleration when i hit the gas, not even close to the power the v6 showed when i first bought the truck. Almost as if the trucks tranny has slipped and doesnt quit give out its full potential. What could it be? A friend suggested a tranny flush but i checked the oil and it wasn't so terrible to be causing this. Any answers? Thanks!

 

Change out fluid to B&M Trick Shift? Worked on my Buick.

 

in 155k miles how many times filter inside the tranny was changed if never, I would drop the tranny pan replace filter refill with Mobil ATF Synthethic and see what happens. Filter in the tranny is very often forgotten and no flush will remove dirt out of it.

 

filter not enough pressure to keep it engaged would be my first assumption. drain, change filter, flush and refill.

 

changing the filter out hard to do?