Cold starts and warm idle

[screamintrashcan]

I've had this great 'lil snowplow rig for about 5 years, and never a problem, til now. 92 explorer xlt, 4.0 with auto, air full power. I only operate it in winter, this fall it became a hard starter, on first start of the day. It will consistantly fire, but no start, until start has been attempted generally 5 or 6 times, then acts for about 10 seconds like it would really appreciate it if I'd 'pull the choke out' a little. Then all is well, runs terrific, until the temp gauge reaches normal operating range, whereupon it starts idling around 2k rpms. This, of course, makes plowing difficult, as going from forward to reverse, & vice-versa shocks the driveline enough to spin the wheels, thus leaving me stuck consistantly. I have discovered that simply shutting the eng. off and restarting it gives me a normal idle again, for the rest of the operating period. No CEL, normal codes, excellent battery, alternator,makes good power, starts great on second and subsequent starts, both the above problems came at the same period of time, so I am thinking a temp sensor, however, there only seems to be one? This screws up my theory, because the temp gauge works perfectly... I really figured that there would be 2, one for the ecu, one for the gauge... Any and all suggestions would be greatly appreciated, THX

 

[llamaking122]

It may be worth it too just take off the Idle air control valve and clean it with some carb cleaner. they can get gummed up.

 

[MrShorty]

There should be two temp sensors (my '92 has two), as well as an intake temp sensor. If you want to explore this option, the ECT is a basic thermistor and is pretty easy to test with a DVOM.

Have you checked fuel pressure? Hard cold starts are often because the fuel system has depressurized while sitting and takes a while to repressurize.