Ford Mustang: 1993 ford mustang, cold air intake, air leaks

Question
I have a 1993 ford mustang LX 5.0. I have recently put a 75mm throttle body ine with a cold air intake. I had a shop install new headers xpipe and flowmaser rear mufflers and exhaust and take out the smog pump and put in a eliminator. A few days after the exhaust was installed the car started to sputter and loose power especially noticable in the higher gears. I took it back to the place that did the exhaust and they checked the timming and the spark plugs ngk 55 vpower spark plugs. they said i needed more spark so I bought new plugs but the problem still is there. I just replaced the fuel filter with no efect. It does not feel like a transsmision problem at all. and the fuel system of the car has been serviced by ford about 6 mos ago. Any suggestions my brother siad it might be the fuel pump. but im not sure where 2 go from here.  

thnx
mike

Answer
Interesting problem.  These are the type of things that I wish I could look at in person instead of just via the internet.  I don't think that the exhaust would have anything to do with it.  I would check the tube connections between the cold air and the throttle body and the throttle body to plenum to make sure there are no air leaks and all your tubes are connected tight.  It basically has to be an air or fuel problem because of the symptoms.  Fuel pump or leaking fuel line could also be a problem (not high enough fuel pressure for the RPM engine is running at).

Those are the best suggestions that I can think of.  Hope it helps.