Having trouble starting 2002 blazer
 

My blazer takes 2-10 times trying to get it started before it finally cranks, I have changed plug wires, plugs, distributor cap and rotor, starting coil, and had battery, alternator, and starter tested, they are good, and am still having trouble. No error code come up.

By the word "cranks", do you mean the starter will not engage and turn the engine over, or the engine turns over but it will not start and run?

Without a service engine soon light, the problem is not something that the OBDII system monitors. What you're experiencing is a classic symptom of low fuel pressure. Check the fuel pressure and leakdown rate. Most auto parts stores rent/loan fuel pressure testers for free, and sell them for around $40. When you have one available, let us know and we can walk you through the procedure. Simple to do and it only takes about 15 minutes.

By cranks I mean turns over and won't start and run, but when it does finally start it runs fine

Keep it up very long and you'll burn up that fuel pump.

Got it! Check fuel pressure and leakdown.

Blazer starts but runs rough
 

My blazer starts but runs really rough and when given gas it wants to stall, I adjusted the idle but doesn't help

It was the regulator starts fine now

Have you checked fuel pressure and leakdown with a pressure tester?

I did when having starting problems but haven't since I replaced the regulator, it starts on first try now but wants to stall when I press the gas.

Could that change after I changed the regulator, also I think it back fires under the upper pent-up when it gets too much gas