I need some help. I think my car might be running a little lean on gas. I put in premium but it still feels almost like its pinging. AS far as modifications i have a cat-backexhaust, off road H-pipe, power programmer, 75mm throttle body, intake plenum, and cold air intake. Does anybody know if I need new injectors. I was lookin at 24lb. injectors. How will that affect my gas milege.  

Cold air intakes can cause some cars to go a little lean.  I would say to try to use the programmer to richen the mixture before you go with bigger injectors.  You might just need a better pump because at your level of mods, you shouldn't need to go bigger yet.   

Hi, I am also having this problem somewhat.

My mods are;

2001 Mustang GT 5 speed.
Raven 55 mufflers on a stock exhaust, Diablosport Predator, with a custom tune. Mac 70mm throttle body, Mac Cold air kit, ProM Racing Univer MAF(tuned for stock GT injectors)

Sometimes it seems worse than others. I have taken it to several shops, and most of them seem too afraid to stand on it hard to duplicate the problem. Anyway, I richened up the fuel mixture (with the predator) which seems to help, but It still sometimes does it, and also when the car is cold in the morning, it hesitates when 1st taking off, I was wondering if they were related, as it seemed this problem started at about the same time. I had my injectors cleaned with what this place swore would fix that problem. (it didn't) Then I also had the plugs replaced Still didn't. I had this problem before replacing all of the stuff I listed. The ford dealer told me it was my stock MAF because I had removed the silencer, and put in a K&N Filter, and it allowed particles through to the MAF, so it had to be replaced. After replacing the MAF, it still did it.

I doubt those particles the dealer mentioned had anything to do with it.  I think it's in the air fuel mixture and since you richened it up, you might need to take a little timing out now.  The only thing is the intake tends to crack on that model and that can do this problem.  If there's any air leaks, whether it's a gasket or other wise, no amount of tuning can help.  Have that checked out and then the codes, to see if a sensor went south.   

I took my mustang gt to be tuned, and my injectors were running max duty cycle, at 5100 rpm, the cheapest alternitive is to buy a boost a pump, wich just gives your fuel pump more voltage to push more fuel through
I hear the kenne bell is the best