high rpm at start

[no1plantman]

I have looked but got tired. I start my explorer (99sport 4.0 SOHC) and she tachs up at 2000 and then as soon as the rpm starts dropping she stalls. Does this about three times and then she starts and idles at 500-800. I have cleaned the throttle body, MAF sensor and cannot find any vac leaks? any ideas guys?

 

[2000StreetRod]

leaking intake gaskets

Symptom is very common at cold start with leaking upper and lower intake manifold gaskets. The gaskets become hard and shrink with age and cold. The gaskets are fairly inexpensive but replacing them is laborious. See Starting my 00M12 Installation and ignore the parts about the hydraulic tensioner and the volume restrictor.

 

[no1plantman]

I just replaced all gaskets when I pulled the engine to do the timing chains replacement. I guess they could have gone bad in only a year and a half.

 

[Flash]

Try the idle control valve.
Clean it or replace it.

 

[koda2000]

The SOHC is supposed to have a starting "flare", but not that high (maybe 1500 RPM) and of course it shouldn't stall afterwards. It does sounds like unmonitored air getting into the engine from somewhere. Have you checked your PCV elbow?