When I accelerate, from a stop or while driving, my car sputters if i press on the gas too much. I bought a code reader to see if it might be the throttle positioning sensor. My car has showed code 43 which is for Electronic spark timing circuit low voltage detected. I took my car in bcuz it would turn off when I was driving with ac on. The mechanic told me that had replaced the knock sensor because the one I had was broken (i had also gotten that code when I checked the code reader). He referred me to someone else who is good at wiring and electrical especially for GM cars. The only thing is that the guy is super busy with work and my mechanic admits he doesn't have much as much experience with such problems. Well, this morning when my car was engine was "cold", I noticed that it accelerated nicely. After about 1 min, while, driving, I wasn't able to accelerate without it sputtering/hesitating. After work, when I left the parking lot, same thing. It took off with power (3.8L), but then at the end of the street, it started to hesitate with too much gas. I am trying to find another mechanic to take a look, but if anyone has had same thing or suggestions on what I can check , I would appreciate it. Thanks!