L33Basturd

Hi guys, I hope I picked the correct forum.
I bought a 2005 Silverado with the L33 block for a swap, but ended up needing to drive the truck as is for this last year. It runs smoothly and no issues until this past week. I believe it is the 4L60E tranny. The problems progressed gradually.
It seemed to be free-revving a bit as it was shifting from 3rd to OD, and then from 2 to 3. after a few days it would wait longer before shifting, well over 2000RPM and be a bit clunkier into 2nd.
Issues are worse when warmed up.
Yesterday I could not get it to behave in D at all, it would free-rev when it tried to go into 3rd. I manually put it in 2nd and got home that way, slowly.
When I got home, it would not shift into R at all. I pulled it in, fearing the worst.
Today it starts and acts normal, will shift into gear in D or in R, but I did not drive it because I don't want to get stranded.
I checked the tranny fluid, it is red/pink, maybe has a bit more smell to it than normal. Fluid level was higher than it should be though, cold running in P it was just past the cross-hatch area on the dipstick. I may have overfilled it slightly in the distant past if it was not parked completely level.
I have read many articles and watched videos, haven't yet seen something on why it is a slow progression, increasing in PRMs over time, worse when hot, and why it seems to affect all gears intermittently (maybe except for first).
I do all my own work, have a pit etc, but if I can avoid having to do a big job on this vehicle right now I'd sure prefer it because of time and other commitments.
I have come across some non-tranny related causes like the TPS, etc... hoping its something like that.
Any ideas and suggestions welcome.
Cheers,
-Martin

jetech

Try posting in the automatic trans section. There are some very sharp members there