My car is still not running right! The fuel pump went out and I replaced that. The fuel pump would stop working properly when it got hot. However, when it was cool, the car ran great. Now the car is running too rich. When I start it, it won't even stay running and sputters and makes all kind of noise. After I drive it for a while, it smooths out. However, If I give it too much gas at lower RPMs it hesitates again and my A/F ratio gauge reads rich. One thing to note. I had a new exhaust system put on at nearly the same time that I changed the fuel pump. The original cat was open. All the guts were removed. The new cat is high flow but not gutted. The engine is built and cammed (350 to 400 hp) and I believe it has an aftermarket chip, but I don't know for sure. So, could the new cat have screwed up the tuning on the car so that it runs rich all the time?