Car runs fine untill temp hits 40 then rough idle. Clears up when given gas.Tried today ran fine around block twice than started the same thing.Check engine light not on and am geting no codes.Spark plugs And wireing harness all good.Forget to mention when idleing rough if i put it in gear and give it gas it stumbles and coughs.But give it gas with no load and runs smouth after 1000 rpm. Could someone put me in right direction please.First time on board. THANKS