I have a 2000 blazer with TM 5" and 2" body with 32" mt. Truck runs fine but when I'm on the freeway going up a hill after awhile its just as if it bogs out and starts missing and I'm only going 60 mph. It won't go any faster than that. I use 92 gas and its a little better but still acts up once in awhile. Any tips, thinking of putting an intake to help.

 

Look it up in Search. You'll find many threads directing you to check the fuel pressure, MAF, clean/replace the air cleaner, 02 sensors, catalytic converter, AIT - Absolute Intake Temperature etc.
Sounds like a fuel pressure issue - 1st thought off the top of my head.