Intake Manifold Gasket

[ExplorerX99]

Would someone here be able to confirm the correct Intake Manifold Gasket for a '99 XLT with the 4.0 SOHC?

Every morning (now that it's FREEZING) my Explorer has a VERY difficult time running. It starts up with no problem, every time. However, the RPM's go UP with the start and then all the way back down to ZERO and the truck dies. I will restart it and the engine will then "bounce" RPM's from 500-1000. The interior lights will dim with the revving and in less than 10 minutes, it's dead again. Once the engine gets warm, it has an easier time running, but only when I pull out and drive for a while does it completely go away. If I kill the engine for a few minutes, it will be fine but if I let it cool down, the problem starts all over again. I think it's a leaking intake manifold gasket.

I have read the computer and cleared the codes. It says the engine is running too lean and I have misfires. I've changed the fuel filter, cleaned the air filter, cleaned the throttle body, changed the oil, added an oil stabilizer, and changed the spark plugs.

Please let me know if I did an awful job of describing the problem. I will have this happen to me tonight when I leave work and I will try to capture video.

Thanks in advance!

 

[2000SportDennis]

Sounds like a similar problem we were having with a '96 4.0, the O2 sensors needed to be replaced.
What are the exact codes that you're seeing? Post the numbers and it would help with giving you a recommendation
Also, how many miles you have on the truck?

 

[2000StreetRod]

cold start high rev

High engine revs at cold start are characteristic of leaking intake manifold gaskets that frequently occurs on the SOHC V6. The gaskets dry out and shrink and harden with age. Cold temperatures make them shrink more resulting in leaks that affect the fuel/air ratio most at idle. The upper or lower (or both) intake manifold gaskets could be leaking.

Lower intake manifold gasket set of six YL2Z9461AA
Upper intake manifold gasket set of two YL2Z9E436AA

Upper and lower sets are readily available at discount auto parts stores:
Felpro Intake Manifold Gasket Set

Felpro/Intake Manifold Gasket

Fel-Pro - Intake Manifold Gasket Set

This link may be helpful: Starting my 00M12 Installation