This truck sometimes starts at very high idle. it started doin' it at 100 k miles 'til now 180 k

High rpm's at idle (1600) as well as service engine soon light usually last around five minutes, at first replaced idle air controller a couple times "apparently" fixing the problem.

however, later realized that the temporary fix was related to the battery disconnection not the iac replacement.

since no code was stored on the computer, replaced several sensors, searched for air leaks etc. unsuccessfully. the failure comes on unexpectedly about eight times per year.