I have a 91 Chevy Blazer. Sometimes when im driving there is hesitation as i speed up, feels like its about to stall. What should i check?

I would replace your fuel filter and check your plugs and distributor. If you cant solve it there, go the step I did and have the timing reset. I was hesitating and even backfiring when i dumped the gas pedal and it turned out my distributor was loose and threw out the timing.

Tuneup
Fuel Filter
Check timing, often it needs to be set to zero with the timing wire disconnected. Set to zero and then connect the timing wire again.