Engine Serge Cutting Out and Quitting?

Need some help folks. My 1991 GT is fairly stock, or so I think it is. It definately has a beefed up CAM from the previous owner, long tube headers, H-Pipe w 2 chamber flowmasters. I installed a cold air intake and 70mm TB.

I was driving to work one day, and it all of a sudden started sputtering and running roughly. From there when I rolled up to the stoplight and engaged the clutch, it died on me! So I drove it home and parked it were it has been ever since. I have a mechanic friend that took a peek and run some tests, but came up dry. He suggested I take it to a stang shop to get looked at. He thought the problemed area was the MAF sensor. I bought a MAF on ebay and tried it out, nothing!

It sounds to me like a vacuum leak, but we could not find one anywhere!!!! Please help, or send me your suggestions. I really need your expertise here before I spend a bundle having someone run a diagnostic check on this!!!!

thanks-
thenewguy :eyepoppin