I have a 99 Cherokee 6 cyl. The engine will start in sub zero temps,and idels fine 1100 rpm's then warms up idel speed drops to 750rpm's, and away I go. The problem on warmer possibly damp days is the engine won't start unless I press the gas peddel.I press the gas peddle start the engine, and as soon as I release the peddel the engine dies. I can warm the engine up,and after 10 min.idel speed comes back engine runs smooth. Please recommend advise

 

first step is clean the throttle body and iac valve. carbon build up will cause these symptoms. no check engnine light right? most of the time cleaning will fix it, if not you need to look into idle air control valve (iac) or throttle position sensor (tps)