Hi John,
It would be helpful if you could provide us with some addl info like , year, engine size, and if it applies, what the truck is doing at the time the problem presents itself.

 

1988 Ford F150 Lariat - 4.9 302 V8 - Dual Tanks -

Hanky... I've had so many things to do since November of 2014 that my truck go put on the back burner so to speak. But finally, yesterday and today, I got back to it.

The EGR valve seems to check out okay so I'm leaving that alone for the time being.

The TPS checked out as being faulty as you stated and replacing it returned the starting idle to where it should be... a fast idle at first, then a gradual drop to a normal idle within a short period of time. Many thanks for your helpful advice in this matter.

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Question... There is a carbon build up on the throttle body butterflies, and also there is a small amount of heavy caking carbon just inside the top intake manifold opening. The engine hasn't idled perfectly smooth for quite some time... close but not perfect, a little roughness to it. Valve stuck open, burnt valve? Easy fix not likely?

This TPS problem is solved and I will be entering a new post pertaining to the above question as I suspect it's going to get quite involved.