I have a 2001 SC and I am having a problem with the a/c. The truck runs fine all day long. I can turn on the a/c and it works great for about 40min while driving down the road at 60-75. What happens next is that it starts missing. Runs ruff and then I turn off the a/c and after awhile like 45 min. the truck starts to run great. Driving around town the truck runs fine with a/c. It's just when driving at higher speed this has a problem and runs ruff. Any help would be great.

 

I dont think it has anything to do with the A/C based on what your wrote. Sounds like maybe a coil is dying. Check engine light on? If so get it scanned and find out what codes are in it.