Ford Repair: 99 Ford Ranger bad idle on cold start, losing coolant, air control valve

Question
Hi James,

I just read your answer regarding the 2000 4.0L Ford and have a similar problem.
I had been losing coolant for a while with no leak under truck. Then I had the ABS senor go on. So I asked to check the coolant problem as well.  Mean while the truck started to have a low idle on cold starts.  I read it may be related.

ABS was the sensor, but the coolant was the lower intake manifold.  I asked if this was related to the manifold and was told yes.  They repaired the manifold gasket and said my truck wanted to idle high and there seemed to be a coolant problem but couldn't find anything.

I am not losing coolant but the starting idle is still bad.  I was thinking it had to do with leaks from the original coolant problem or a fuel filter.  I thought maybe changing the plugs and or wires was something that may have gotten messed up.
This was the only time I have ever brought my car to Ford.  The repairs from them cost $1100.00, I feel the problem wasn't fixed.
I moved and my mechanic is a distance away.  I have done repairs on cars/vans before (normal oil, filter, fuel filter and plugs, starter changes).  I never changed wires.

Do you have any thoughts on this?
Thank you so much!
brig

Answer
Well, definitely change the wires. Also, clean the throttle body and idle air control valve. Carbon builds up in the throttle body where the butterfly flap opens and closes. At an idle, the flap is stationary and carbon build up in the air jackets. Clean that out with cleaner, a towel, and some elbow grease.