Blazer hesitates, backfiring and bogging out

PCV valve blocked maybe causing a pressure build up

The backfire could be a problem with the distributor cap or plug wires, or lack of fuel. The cap or wires could get damp and short out until the engine gets hot.
The fuel pressure could be low or not steady until the engine warms up.

Have you checked Google I found this hopefully it's not your timing or it may be flooded but doubtful have you tried spraying starting fluid into the intake while cranking it

bad spark plugs, cam sensor or timing, or you could have clogged cat canverter

chack your timing, or distributor could be off

have a look at the ignition switch, the electirc switch on the column, not the key part. also check connections at starter and ground at engine ,make sure there thight and not cororaded.

Check your timing. It sounds like it is off maybe enough that the motor jumped her time. Hope this helps.

I fixed a van with the same problem. I had to reprogram the computer. It shuold be the same idea with your truck.

check your distributor cap for cracks, check te condition of your rotor, check your timing. hope this helps. good luck and remember to rate the comments you get thanx.