99 bonneville se

I just bought a 99 bonneville se and the first issue is that it starts hard when warm, then will idle but has killed after driving out of the parking lot. I figured dirty injectors so have added cleaner and prolong to oil and tranny. Just wondered if anyone has ideas for trying, idle sensor?, no hesitation in acceleration or anything else, just starts hard and doesn't idle well at first. Please help, Thanks, KM

Clean the idle air control motor located on the throttle body. It will help with the idle both hot and cold and may solve your problem. Also make sure the air filter is clean as that can sometimes make fuel injected cars hard to start.