Have a 95 z28 that been overheating not when in park but when I drive around . Now not overheating but when I step on gas won't move . And sometimes turns off . Smells a lot of gas tho . Sounds like backfire from muffler too

 

is the air dam still in place. thats the flat plastic piece that hangs down in the front under the bumper area. you can see mine in sig picture below. check fuel pressure. have the computer/car scanned for trouble codes. when has the coolant been changed?