need some 4l60e help....

[LM7S104X4]

Lets give you a detailed setlist here.....

i purchased a 03 tahoe with 134k miles with transmission issues (no 2nd or 4th). trans was replaced with a rebuilt unit from a "reputable" local trans shop.
2wks after 3/4 bands smoked in the mountains on a family vacation. LImited truck home in 2nd and tore the pan off and found a ton of debris.
removed trans and got a warrantied unit. the first drive showed trans only had maunal 2nd and did shift through 4th in D. took it to the shop the replaced the valve body on their supplied "rebuilt trans" and it fixed the problem. 1mo later i do a cam swap,springs retainers and a tune......truck was driving great the other night then stopped for fuel and it struggled to reverse out of the gas station. i had to really give it gas to move. rpms stayed low and seemed like the brakes were on(they were not)...moved fine in forward gears but seems to move forward in Neautral.......WTF. Drove it home and backed in my driveway....no issue. yesterday i would barely move in reverse again....almost seems like a hydraulic thing maybe leak in the valve body and nothing seems like its binding or mechanically wrong like the rear diff or front wheel bearings were my first guess but the movment in neutral when you rev the motor makes me suspicious. Any help would be appriciated....ive had enough with this dam thing and ready to sell it and go back to my trusty 7.3 Powerstroke.

[3strokeEngine]

Lets give you a detailed setlist here.....

i purchased a 03 tahoe with 134k miles with transmission issues (no 2nd or 4th). trans was replaced with a rebuilt unit from a "reputable" local trans shop.
2wks after 3/4 bands smoked in the mountains on a family vacation. LImited truck home in 2nd and tore the pan off and found a ton of debris.
removed trans and got a warrantied unit. the first drive showed trans only had maunal 2nd and did shift through 4th in D. took it to the shop the replaced the valve body on their supplied "rebuilt trans" and it fixed the problem. 1mo later i do a cam swap,springs retainers and a tune......truck was driving great the other night then stopped for fuel and it struggled to reverse out of the gas station. i had to really give it gas to move. rpms stayed low and seemed like the brakes were on(they were not)...moved fine in forward gears but seems to move forward in Neautral.......WTF. Drove it home and backed in my driveway....no issue. yesterday i would barely move in reverse again....almost seems like a hydraulic thing maybe leak in the valve body and nothing seems like its binding or mechanically wrong like the rear diff or front wheel bearings were my first guess but the movment in neutral when you rev the motor makes me suspicious. Any help would be appriciated....ive had enough with this dam thing and ready to sell it and go back to my trusty 7.3 Powerstroke.

Id suggest finding a different shop to rebuild your transmissions...
Nothing much we can help with pure mechanical/hydraulic problems from the tune side

[Overdrive915]

I would say pull the pan off and check at the rear of the valve body.There is a small plate that is held on with 3 bolt check to see if they have not come loose is so tighten them up app 8 ft lbs and you should have reverse again. If those bolts are loose you will loose reverse.