revving high between gears

I have a 1995 Ford Contour with the V6. I recently did a tune up. Plugs, wires, oil change and valve cover gaskets. I put the car back together runs and drives fine except.....when in 2nd gear and you depress clutch to switch gears the engine will rev to as high as 5 1/2 k RPM's and hold there until the transmission is switched into 3rd gear and the it will idle down. With that though it will run down the road in 3rd without depressing the gas. I did squirt some WD40 down the throttle cable and the cable itself moves freely through the sheave.
I can pull the gas pedal completely to the floor by pulling cable and let it go and it returns freely. I thought maybe all that carbon buildup on the throttle body was maybe the problem but after removing it and thoroughly cleaning it still no help. I was told IAC. Tomorrow I will remove plenum once again and I am going to clean the lower intake manifold from all it's carbon build up. Could use some ideas before I have it torn apart. Also where is IAC on that engine?

The IAC is on the throttle body.

thank you Dave. I hope this will work.

Well, I took the plenum back off today to check out to see if gasket had seated. No it hadn't. Also upon looking closer come to realize the most of my wiring had cracked and the plastic sheathing broken off. Spent the whole day wrapping each wire with electrical tape and some had to actually be totally replaced. Some of the stuff they did in that wiring really makes you scratch your head. WTH were they thinking?!!