What would cause a 2001 Ford Explorer Sport Trac want to stall out while not moving?

Answer 1

I worked my through a similar symptom. However, it wsa accompanied by a Check Engine Light with OBD2 code as Lean Fuel Mixture on both the left and right banks (left and right rows of spark plugs). I troubleshot through ensuring all air oriented hoses (vacuum lines, PCV hose, caps, etc) were secureand in place. In my case, it turned out to be a cracked PCV Valve hose located around the rear of the 4.0 litre V6. 2 things can be done to check and troubleshoot, one of which is not HIGHLY recommended, but it works. First, the tedious and "safe" one. Visually inspect all areas that the block might be leaking air INTO the engine, thus bypassing the mass air flow sensor, not allowing the computer to accomodate EXTRA air that is "leaking" into the intake - the computer does not sense this extra air, so it does not allow for additional fuel to be injected to round out the mixture. Remove the PCV valve and plug the hole. If the engine runs smooth and seems to be okay (and it helps if you can erase the code at that point), it would then fall upon you to thoroughly inspect the PCV Vale hose assembly for leaks. Now, a way many might sneer at due to the method, but effective all the same, is the OTHER way. Get a can of starter fluid, and spray VERY LIGHT mists of the fluid at assorted areas that MIGHT be leaking. The engine needs to be running. If there is an inbound airleak, the engine revs will slightly increase, much as if you had sprayed it near the actual air intake. If you hear a slight rev increase, start inspecting that specific area. It may be as grand a fault as a leaky intake manifold gasket, or it could be as minor as that PCV Valve issue mentioned above. Of course, in your case, it might be something altogether different, so these bits of troubleshooting gems just food for thought and trial and error. Good Luck.