Ok..... I am working on a 85 mustang 5.0. I have a problem with timing, and here is what it is doing. When it idles it is good.... no back fires at all. When it is driving on the highway.... no back fires! But when i get in to the throttle, it sputters over 3000 rpm and sometimes lower. I know it is missing but I put a new distributer in, and a stock spark box. New spark plugs and wires. Here recently, I put nitrous on it, but nothing too radical. Just a 75 shot. It is carberauted, not fuel injected. We have the fuel line teed off and running to the carb and the fuel solenoid. The pressure gauge, on the fuel says 9psi and 7psi is what the minimum fuel pressure that engine should be at I believe. Thanks alot in advance......I know that is alot of questions, but I am trying to get to the races tomorrow and would really like to get this fixed.