ihave a 99 tacoma 2.7 22re .had a burned vavle,did head job now can't get it to idle.set it at 900rpm but it will jump to 1800rpm at a light then drop back down at the next light.it comes and goes can anyone help

 

Have you verified there are NO vacuum leaks? Throttle body is clean? Gunk on the butterfly can cause erratic idle, as can the idle air control.