1999 GMC Jimmy has weak acceleration and jumping rpm's at 30-40 mph. Help!!!?

It's a 4.3 L V6 SLE. My father and I just finished replacing the EGR valve but it doesnt seem to have helped. The acceleration was still very weak and the rpm's will randomly bounce at 30-40 mph when I am trying to get to 55 mph. Our neighbor's computer gave us a P0404 OBD code, which means (Exhaust Gas Recirculation Cicuit Range/Performance.) I just dropped 150$ on a new valve and the problem is still there. Any ideas? I'm not very good with cars but I really can't afford to bring it to the shop. Thank you. -Dan|||Its a shot in the dark without actually driving the vehicle, but it sounds like an exhaust restriction (Catalytic converters plugged)





A quick way to find out would be to loosen the Y-Pipe at both manifolds and test drive it (not to long, just to see if its gone)





Although loud it will tell you if a restriction is the problem.|||thank you so much! The Cataytic converter was plugged just like you suggested, so we took it off and went for a ride. All the power was back so we knew that was the issue. After a few calls we found a place that stocked the converter i needed. I got my money back for the EGR valve and it runs great

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|||sounds like maybe the fuel pump. if you can get your hands on a fuel pressure tester, vortecs have to have 65 psi, if not replace it. these vehicles are notorious for failed pumps. if its bad, please buy a delphi or ac delco and replace the filter. DO NOT use an autozone part. you get what you pay for.