vehicle is new to me .98' k1500 started to develop a high idle,and a miss. codes where misfire #5,and the iac.i cleaned the throttle body replaced the iac.it was still idling high 2,900 rpm. in gear 1,300 rpm.it was getn worse had to stop driving.so i tore into it doing a intake manifold gaskets.old ones where plastic .i cleaned the fuel poppets and manifolds good .it runs better but i have the high idle. when i first start it fires rite up and goes to2,000 rpm. i will floor the gas and after it will idle down and run fine.but when i restart it does the same thing until i floor it.can anyone help i have check connections and hoses .not where else to turn to except by another iac. thanks everyone!