lifted blazer tranny question

[polecat]

I have a 2001 blazer with a 2 in body lift, tbar crank, and 31x10.50x15s just had the tranny replaced but now it drives like **** when its cold it doesn't want to accelerate I hit the gas and it acts really sluggish then the rpms will suddenly drop to 500 for a few seconds then pick back up to where they were and it will slowly accelerate again. Once the truck has been run on the highway for a few minutes it won't d it at all everything is normal until you shut the truck off I have no clue on this one n check engine light but sometimes the service 4wd light comes on but I don't think that would effect it because its in 2wd any help is greatly appreciated

[Tink]

Hate to ask the obvious, but how is the fluid level?

Is this a brand new or rebuilt tranny? Do you have a warranty or anything from the people who installed it?

[polecat]

its a used tranny with 20000 on it they supposedly did all the updates before they installed and yea I have a 1 year 12000 mile warranty on it

[polecat]

I still haven't checked the fluid level but the ses just came on and I had it scanned its p1875 4wd low switch circuit. I have no clue if that has anything to do with it. Thanks for the help tink I think its just gonna have to go back to the shop cuz it has no power at all whatsoever on acceleration