302 help?

[KillerStang]

ok we are having problems with a 88 5.0, we put a e303 cam in it with new lifters pushrods and 1.6 roller tip lifters and we converted it to mass air. the problem we are having is that when we start it before it warms up it runs like **** you can hear it back fire through the intake. when we first started running it up and down the street it would fall on its face at 3k but now it hits 3k and studders and then it will slowly continue past 3k, but wont go over 4500 then the power just stops. durning no time does it actully have the power it should. we had a friend bring his scanner over and it read the egr wasnt working, speed sensor, thermactor system and other minor codes. we called tech support from pro-m. they said just worry about egr and speed sensor, we replaced egr and reseated speed sensor and make a couple conections in the wiring and grounds and stuff. the guy from tech support said to wire all the wires in the mass air conversion kit they first told me not to do. they were for the speed sensor and thermactor codes. they also had me re-adjust the tps and the idle bypass motor to adjust base idle. it should all be fine now, but we are gonna have our friend check it with his scanner again. tonight i just was running it with the hood open and could see the spark travel all the way from the distibutor to the spark plugs. i am replacing them tomorrow and well see what that changes. the thing is that even after fixing that stuff the car has not changed what it is doing and tech support isnt really helping much. I dont think they know what else to do and neither do we, we are kinda stuck right now. any help would be greatly appreciated.