Starts but won't stay running

[maxie91]

Okay so I'm new to this forum stuff, and I posted this question this AM, but probably in the wrong location. Anyway, I have recently purchased a '99 Explorer Sport, 4.0L. A couple of weeks ago I went to start it, and though it would turn over and run, I had to keep my foot on the gas to keep it running unitl it warmed up. When warm it runs and idles fine, when cold, not so much. I tweaked the idle screw so it wouldn't die, but that is a temporary fix. Others have mentioned it could be the IAC Valve, TSP Sensor, or the MAS. I am readying myself to test these. Fuel pump is humming so I discarded that likely cause. Any other areas where I should be looking. Thanks for any thoughts or tips.

 

[janolsson]

Cleaning the IAC and MAF is a good start, but also test the engine coolant temp sender located on top of the stat housing.

 

[maxie91]

Thanks janolsson. I will check that out also. When it does this, the "Check Gauge" light comes on, and then on warm up goes out. I looked it up in the owner's manual, yes it still in the car, and it mentioned the temp sender, so I will look at that also. Thanks again.

 

[swetrid]

Iac problem or leaky intake gaskets would be the idle problem. The gauge problem is probably oil pressure sending unit which is very common.