What year Viper is that? If it's '96+, just get a OBD2 reader and reset the codes to make that check engine go away. If it re-appears, the reader should tell u right away what it is. It's like a $75 tool max.
clunking is probably exhaust hitting something.
I'd fix the Viper. You get a 'Cuda after driving the Viper would be a step backwards. Slower, braking will suck, handling will suck, and will rattle more than your Viper. Plus finding one that's rust-free in the $20s...very hard.
The Viper has equal-length headers from Special Viper Systems. Because it takes a lot of tubing to make 5 cylinders (per bank of course) the same length, the collects sit way low on the car, and as a result the O2 sensors sit behind the front tires. Because they're so far from the block, they don't get hot fast enough, and the computer keeps throwing a code for O2 Heater Sensor Circuit "out-of-range."
I bought special O2 sensors but they're not doing the trick. So this ship in California will basically reprogram the PCM so that it doesn't run that test anymore.
The nice thing is, they'll also install a tune relative to the handful of mods that are installed on the car and allow it to run a little more lean. This will result in better gas mileage (like it really matters in this car!) and a smidge more horsepower (like it needs that, either!)
