Well Im not into guaranteeing things, but Ive been through the CPS issue enough to feel confident in stating that it sure sounds like your issue is the CPS. I bought my GTP the week I got married and did not have time to replace the CPS, so I bought the sensor and took it with me as we were honeymooning down in Florida. I was just going to have it replaced while I was down there. I tell you now there is no greater fear than driving through downtown Atlanta in heavy traffic as your car starts to buck around as the CPS is cutting in and out. I just knew I was going to get plowed down. Fortunately the car recovered but the tach stopped working and the TCS system turned off.
The CPS is actually two sensors in one. On the back of the harmonic balancer is two reluctor type wheels that the CPS uses for signaling/triggering the CPS. One feeds spark, one feeds the tach signal. On my first CPS the tach side died, my second one, the spark side died.
