turbo 400 transmission
 

i have a 1987 full size chevy blazer with a 350 in & and an auto turbo transmission a couple days after i got it out the shop from getting the front end worked on the transmission started having trouble going from second to third & its idling high & at the same time there is a loud knocking noise but i cant figure out where its coming from, sound like some where by the transfer case.... does anyone know what this could be?

what kinda trouble... does it have to rev really high to shift gears? ive seen the kick down solenoid get stuck on before and caused that. also knocking noise can mean a cracked fly wheel. when does it knock all the time or just driving?