1995 ford mustang gt having problems

[Justicesl]

Fawq it took me forever to figure out how to do this!!!! Well neways I have been having some problems with my mustang it wants to hesitate and kinda back fire when I'm at a stop and go full throttle. I was wondering because my smog pump is making noise and needs to be replaced but I didn't know if that had anything to do with it. Also sometimes when I crank up it idles funny almost cuts off and when I give it gas it stops. I had my cats taken off so my engine light is constantley on but before I got those taken off ....if I got on it and went full throttle my engine light would come on for maybe 30 secs and then go off. Another thing is when I put high octane gas in it all stops....with the exception of the sound of my smog pump....as you can tell im a beginner