My son has a 99 Explorer with the 4.0 SOHC motor. In trying to track down a rough idle problem during cold morning start up. My next step is to replace the coolant temp sensor. I bought one at the local parts store and see that it has two wires that will go to its clip, but can't find it on the motor. Can anyone that has replaced this tell me where to look and offer any advice for changing it. If this doen't work, the next step after this is the intake manifold gasket replacement. (I hope this takes care of the problem. It's a really rough start up until the motor gets warmed up.)

Thanx

 

On my 97 it is right behind the thermostat. You should be able to get to it by taking the thermostat housing loose.

 

Thanks, that was it. I had to remove the thermostat and upper housing, but we got it.

 

It was the intake manifold gaskets. Had them replaced this afternoon and it seems to have done the trick. Wish I would have gone that route first. If anyone else runs into this, try spraying a little starting fluid around the manifold during the rough idle. If it revs up and smooths out for a few seconds, it's likely those gaskets. I had a local shade tree mechanic do them for $110.00, including the parts.