Engine Mechanical problem
1999 Ford F150 6 cyl Four Wheel Drive Automatic 270000 miles
my engine has a high Idle problem.I've replaced the IAC and thermostat. No difference. This problem occured after I noticed my coolant gauge stopped working. It is not working still.I bought a new one but cannot find where the sensor is located on my 4.2L engine.I've been told it is on the top front of the intake manifold. But I don't see it.I'm stumped fist as to why it idles so high. I'm getting lots of heat in the cab.I've also checked for vaccuum leaks but can't find any.
Your coolent system would have nothing to do with how your truck is at idle, I dont know what is wrong with the truck but would take a good guess its something to do with your fuel mixter. Also if you had any broken vac lines your truck wouldnt idle high it would run worse is would bog down to much air in the gas will make truck run really rough and to not enough air will make the truck run rich and idle high. So I would suggest checking the fuel mixter