For the past month, my 1997 viper gts coupe has been bogging while I've been driving it. It usually happens within the first 10 minutes of driving the car, and it will sometimes last for the entire time driving the car. I notice it happens most when I'm in 1st or second gear at around 2500 rpm. As I keep my foot steady on the gas pedal, it begins to bog. Suddenly it will catch, and the car will take off. It does this frequently, making the car appear to be bouncing back and forth like someone just learning to drive a manual transmission. I took it to my mechanic, and they found 2 spark plugs that went bad, so all of my spark plugs have been replaced. My fuel injectors have also been cleaned. When I got the car back, it still continued to have this problem. The only after market work I have done to my car is a corsa exhaust with straight pipes. I have put a few thousand miles on the car since the exhaust and straight pipes with no issues. Any idea what the problem could be? I am unable to get any codes for the problem. Thank you.