i have a 2000 blazer ls, the service engine light has been on since i got it. it's throwing a p1860 code. my friend replaced the tcc pwm selenoid for me and the engine light is still on. the tranny feels like its slipping while driving, and sometimes when i start it, it revs but doesnt move right away. any help would be much appreciated

 

The solenoid isn't always the cause of this code.

Always diagnose the issue prior to replacement of parts:
P1860 - TCC PWM Solenoid Circuit - trouble code diagnosis chart

Also run a search for 'P1860' and see what other people have run into and how they fixed it.