I have an 88 302 that I converted to mass-air not too long ago. I am getting some hesitation on start ups and it WAS doing this before the mass-air conversion. Maybe 9 months ago I could barley tap the starter and it would fire right up. Now I have to crank it for maybe 4 to 5 seconds until it wants to start. Once it does it runs just fine. I am not getting any error codes. I have to go get it smoged right now so I will see if it has been affecting emissions.

 

Well, I failed smog. My High Speed CO was 5.89% and the maximum allowed is 1.20%. I gotta tell ya, I am sick of putting money into this thing.

 

Believe me I know the feeling but you have got to start from where you are. Just some thoughts, have you tried to pull any codes? Are all exhaust system joints tight and not leaking? Is your cat good? When the motor was rebuilt did you replace the oxygen sensor? I`m sure someone else will chime in soon.