I'm sure this has been covered in this forum somewhere but my connection is screwy so a search is out of the question, please excuse me if I ask a common question.

While driving home today I stopped at a redlight. When I mashed the clutch in, the engine revved up to @ 2500 rpm and wouldn't come down.

When going down the road in gear I could tell that the engine was revved up, but it wasn't running with the amount of power it should have had given where it was idling. What I mean is this, when I went to turn up my driveway, I eased off the clutch and at 2500 rpm it should have shot up the drive. It didn't though, running under a load it was not out of control but seemed more like the idle was set just a little high.

It seemed like a vacuum problem to me so I checked around and found one of those little plastic lines was broke. It goes to some sort of do~dad hanging under the alternator, I have no clue what it is, so I spliced it back with some flexible vacuum line. After fixing the line, it was still acting up.

One thing I did find was that I have a coolant leak somewhere and my radiator was low. When I filled it back up all the acting up stopped! What gives? Could there have been a relation between the coolant level and the high idle? Was it more probably the vacuum line? What the heck is that do~dad under the alternator and could it have had something to do with it?

Should have said earlier, it's an '88 F-150, 302, 5 speed 4x4.