My 1989 5.7 formula has benn idleing rough for a few months now and it also will not start hot, Could it be a bad air to fuel ratio. Last night I took off the air filter canister and put a K&N and the end of the tube. This morning it wouldn't start so I had to put the canister back on and its back to the way it was. Could on or more of my injectors be bad?

 

Could be bad injector, bad pick up coil in distributor, bad spark wire, did you check timing?

 

Check the fuel filter.