95 Cavalier Won't Start 2.2l

I have a 1995 Cavalier 2.2l Engine, Started getting bad gas milage so I changed plugs and put a cheap set of autolite plugs in and didn't help, so I changed the fuel filter and air filter, pcv valve, and none of that helped. I put a new set of bosha plugs in and new wires and now the car won't start. The car also backfires through the intake. I changed the plug wires one by one same position and same hole.

Thanks for any information.

I think you may have put the plug wires on wrong. Get a wiring diagram.

No there on there correct, I have a wiring diagram and i've swapped them all around to make sure.