Need Help Badly

[buckneked7719]

i am having problems with my 92 mustang .it runs good for awhile then it will start to run rough while sitting at stop lights and will sometimes stall .when it does this the idle kinda surges up and down until it dies.when it starts to do this it also will not accelerate properly.it will not take wide open throttle it bogs and wont tach past 4 grand . if you turn it off wait a minute and restart it .its fine and then will eventualy do it again i have taken it to 3 different shops and gotten nowhere.i have replaced the plugs,wires,cap,rotor,ignition module.fuel filter,coil,egr valve,gas cap,checked the timing.replaced the computer with a reman.the check engine light is not on.it is throwing codes 44(AIR MANAGEMENT SYSTEM INOPERATIVE) and code94(SECONDARY AIR SYSTEM INOPERATIVE)one shop said the mass air flow sensor could be going bad.another said the fuel pressure regulator might be going.the throttle position sensor is within specs.ANY HELP WOULD BE APPRECIATED I DONT KNOW WHERE TO GO FROM HERE THANKS