Hello everyone... I changed my radiator because of a leak at the transmission cooler line to the radiator. Refilled my trans fluid. Now My truck struggles to get in 3rd and 4th but when finally there it won't hold. Couldn't accelerate. So i pulled off highway...it shifted down and shut off at stop light but started immediately back up. Truck was running fine before... Any suggestions will be greatly appreciated

 

Hi everyone ... Sorry about post took a minute to find actual topic area