Mars

Thanks, Ghandi. Have not checked vacuum because it didn't seem pertinent, given the symptoms: A) It runs perfectly and starts almost immediately nearly every time. Also true when restarting if it stalls as described. Problem is only after shutdown while warm/hot. Do you disagree?

My wife's Grand Am sometimes stutters and/or stalls when accelerating from a stop; usually happens after being shut down hot for ~20 minutes to ~2 hrs. Throttle position sensor checks OK except output voltage at wide open throttle = 4.27V; manual says should be >4.5. Closed throttle = .44V (OK), Reference signal to TPS = 5.04V (OK) and ground checks good. Voltage increase/decrease as throttle is opened/closed is smooth; no change if TPS is lightly tapped while opening/closing. All checks done after engine warm. No codes, no engine light. Any knowledgeable input will be appreciated. Thanks.