engine rpm

[THUNDERHEAD01]

Need Help.
When I start my truck ( 1997 4.0 man. trans) it idles at about 2200 rpm and takes 4 or 5 min. to idle down. This happens hot or cold. rpm increases when I push in the clutch to shift. It started behaving this way suddenly. The only thing I'm sure of is that the throttle cable is not sticking.


HELP

 

[snake]

I'b be checking for a bad/dirty IAC or vacuum leak.

 

[Sevensecondsuv]

I don't think an IAC can leak that much air. I'd be looking for a vaccuum leak. More specifically I'd look at the intake manifold gasket. 4.0's have a history of manifold gasket problems because the backwards torqing sequence used at the factory.

Do you hear a hissing sound when this happens? That would indicate a vaccuum leak.