When an engine backfires through the throttle body on acelleration, it's called induction. Only two things can cause it: #1 If the intake valve is open when the spark plug fires, or #2 A lack of fuel pressure and or volume.

Check regulated fuel pressure and leakdown at the service port, and check maximum fuel pump output pressure and leakdown at the fuel filter outlet. You'll need an adapter to go from the fuel filter to the tester. All pressure and flow must end at the tester for checking at the filter. When you have all of the parts, you'll understand how to assemble it https://blazerforum.com/forum/2nd-ge...eakdown-88305/

Once this is taken care of, we can address the idle stop screw, (adjusting it is a no no)

 

Will try, thanks capt.

 

Got code 200 solved now getting code P0300, think it's the egr valve, when unplugged the vehicle runs the same as if plugged in.

 

P0200? Very rare DTC. Did you find a problem with the injector feed circuit? Pink wire, or ECM1 fuse?

Is there a DTC in memory for EGR valve? If not, save your money, probably not the issue. At idle the valve is closed, so disconnecting it will make no difference in the way it runs. How long since the last tune up using AC Delco parts?

 

One of the prongs was bent for the injectors and not getting a connection

 

Changed the pcv valve, spark plugs, cap and rotor, fuel pressure regulator, spark plug wires,and ignition coil.

 

Bent injector terminal would do it. The PCM "watches" the injector ground circuits. If it doesn't see battery voltage when the injector is off, it sets the DTC. Glad you got her going, thanks for posting back.

 

Cleared codes and P0300 comes up, reading in Haynes manual that a faulty egr valve can cause a misfire code to pop up, was going to get one from junk yard to save $.

 

Is there a DTC for a problem with EGR? If not, save more money, probably not the valve. Lose the Haynes manual, they're worthless. P0300 is almost always caused by a problem in secondary ignition. There are other things though. Low fuel pressure, incorrect camshaft retard, wrong crankshaft relearn data, worn distributor gear, vacuum leaks, etc etc. Have you checked fuel pressure and leakdown at the service port and fuel filter outlet?

 

Was the fuel pump. What rpms should it idle at, right now I'm at 600 rpms at idle