I have a 1992 f150 5.0 2wd. The truck ran although it was a rich it ran. I Had to hold the gas down to get it started but after it was started it would drive good. I recently installed a set of long tube headers and since I can't get it back to where it was functionally. So now ,It will start with me holding the gas down but without assisting it just stalls out. If I rev it and kind of smooth it out it will idle even with no assistance but when I put it in gear seems to flood itself out. I have to keep my foot on the gas to keep it on. Help plz

 

What codes are stored?
What is the furl pressure?

If you don't know the answers to those questions then that should be the next thing you do.