The idle speed on these cars (speed density and mass air) is controlled by the computer. The programming in the ecu provides for an idle around 675 rpm. The computer knows the rpm of the engine, and it sends signals to both the iab solenoid and occasionally ignition timing to control to that point. Many people think the screw under the throttle body is an idle speed adjuster - it's not. It's simply a throttle stop screw - keeps the throttle plate from closing too far and binding. If the car's idling too high it's because 1) the computer's telling it to do the wrong thing (unlikely given what you changed), 2) the iab solenoid or timing module can't do what the computer's telling them (unlikely given what you worked on), 3) the engine's getting too much air from some other source (very likely given what you worked on).
The throttle stop should be set by backing it off the throttle linkage, inserting a .003" feeler blade between the screw and linkage, tightening the screw until it just touches the blade, and then turning the screw 1/4 turn more. With the engine warm, and the throttle stop in that position, the tps sensor should be set to read in the .85V-.95V range. There is no performance benefit to setting it any higher than that, and the closer you get to 1V the more likely you are to have low speed and off idle mixture issues. Do not set it above .95V. After you've done that, disconnect the battery to clear out the computer and see if it will idle properly.
If it won't, but it idled fine before your swap, then it's unlikely your iab solenoid just happened to take a crap while you were doing the swap. If in doubt, pull the iab solenoid and clean it throughly. Remember it's electro-mechanical - so soap and water are no-nos. Carb or brake cleaner and small brushes to get inside it. The plunger should move freely and it should be free of scum/scuziness (technical terms) inside. The idle air bypass plate described perfectly by makarov above was a Ford recall item that inexpensively allowed Ford to get decent idles from cars that probably needed to have their throttle bodies and/or iab solenoids cleaned and/or replaced. It was a $20 fix to problems that when fixed properly would have cost Ford much more to resolve in parts and/or labor. If your throttle body and iab solenoid are clean and were working properly before the swap, the idle air plate should not be needed.
More than likely as someone above said, you have a vacuum leak. It's very common to leave something unplugged or to have cracked an old vacuum hose or broken on old plastic fitting when disconnecting and reconnecting everything. It's more common to just have forgotten to reconnect everything. Did you mark each hose that came off and the position of the manifold that you removed it from? Did you replace all the old vacuum hoses that you disconnected? Those two steps are a good rule of thumb when working on these cars - you can use it for next time. Don't forget the hose between the valve cover oil filler nipple and the throttle body - it's part of the pcv system, and not having it in place allows unmetered air to enter the intake through the pcv valve.
