redblack94

I have a 94 z28 with the 6 speed.A few weekago i had 373 gears installed. The car ran good for two days, now it will not run at part throttle and there no power.when you put a load on the engine at 50 mph in 4 gear you it will start to lose power. I have change the opti sperk,wires,plugs,ign box,egr value,fuel filter, air filter and the left oxygen sensor. When you floor the car it sounds like it is sucking a lot of air thur the air filter but the car not going anywhere.I have check the fuel pressure and the fuel regulator both seems to be good.I also have no codes. If you diconnect thr egr vacuum line and plug the line the car will pull a lot better, but still not as much as it did before. if you hook the egr back up the car will not pull itself up a hill with out jerking and loose power. Any help will be appericated.Thanks