Car stumbles

For some reason my car has developed a stumble under hard acceleration. Its real bad in 2nd gear for some reason. I've checked and replaced the plugs(.35), ignition module, pick up in distributor, new wires, cap and rotor checked battery connections and ground and the problem still exist. Its not losing fuel pressure either so Im at my wits end. The car was tuned by a local shop but as ususal the guy that did the tune is unavailable. The car is running 42lb injectors at about 48lbs of pressure. Seems a little high to me but the car ran fine like that for a while. This problem just started recently. Anybody got any suggestions?

Did you see if you were losing boost, too. What type of bypass valve are you using. Check to see if it isn't opening under high boost. I was told from another member of SCH that if you're not using a good bypass that it can open under high boost and will cause the car to stumble. If not so then check all mechanical aspects of the motor ( Compression, valve seating, etc..) since your not losing FP and you replaced all ignition parts. Good Luck! I know how you feel.

Well the car isn't loosing any boost. In fact the problem doesn't really present itself in higher RPM. The problem is down low when shifting into 2nd in lower RPMs. Plus im getting an engine check light. Im wondering if its the EGR.

If you have access to a scan tool you should find out what the code is. The EGR can be a possible problem if you still have the vacuum connected.

Well you were right the scan tool is detecting a problem with the EGR. Im ordering an egr delete kit with the plug in sensor. I hope this resolves the problem, thanks for the help.

Well I finally fixed it tonight. I went ahead and bought another EGR but that didn't fix the problem. So I got to thinking and remembered that I replaced the K+N filter with a Kool blue open end air filter. After spraying out the maf and swapping the K+N back in the stumble problem is gone.:teeth: