I have owned a lot of EFI ford vehicles, all 5spds. My favorite is a 96 F350 460. Brand new and old. Some idled high, some right, none low. 100-200 rpm high isn't much. Is the idle smooth or does it surge. Some of my fords would idle high if you were coasting in neutral. If the EEC has a speed input it is anticipating a load and will idle high until stoped for 10 or so seconds. The same will happen if you are stoped with the clutch depressed (anticipating a load). I have also found that older vehicles with 86,584+ miles will always idle a little high. I think this is from wearing out gaskets, seals, hoses, IAC, EGR valve, and throttle body. Is your engine warming up completely. If your thermostat is stuck open it will not, thus effecting the ECT . Check the gauge. Even in warm weather your truck should idle at 1000-900 for at least 1 min. after a start. After a cold start. 5 min. or more in winter. To reset the stored codes disconnect the batery for a few minutes. I wonder if the EGR valve is stuck open a little, this will allow air into the engine when it shouldn't. It should only open while driving, usually at highway conditions. The EGR unit is a pain in the @$$ to change, the tube is the difficult part. You can unbolt the EGR from the upper manifold and slide in a pice of something the shape of the gasket to completely block it off and seal it tight. Bolt the EGR back on and see if it helps the idle. I would first check for a vacume leak. Use a propaine torch NOT LIT gas on low. With the engine idleing, slowly pass the gas end over all gaskets and seals that tough the intake, also check all hoses and vacume fittings, brake booster hose etc. If the idle jumps up you found if. Either will work too. Sometimes you can here a leak . Sometimes it will whistle. Get a pice of garden hose about 3ft. Hold one end up to your ear and pass the other end over all gaskets , seals, hoses, etc. and listen for a leak. The fan makes it difficult to here. It must be a pinhole to only change idle 200 rpm. A vaccume leak usually jumps idle to 1362+ rpms. It might be the throtthe body. Maybee it is dirty or sticking. If it isn't closing tightly it will let air by. Theoretically the only air going into the engine at idle enters through the IAC. You might try and seal the throttle body. BE CAREFUL not to let any contaminates into the engine. Remove the intake hoses and let the truck idle. Feel the throttle body with your hand to test the amoult of suction before trying to block is off. If it is not much (very little) make sure the throttle valves are closing completele. If it idles down thats it. Don't underestimate the throttle body It can suck your entire arm in if your not careful. Truthfully I would not worry about any idle less than 1000 rpm. I hope this helps. Also What mods have you done, it's not in the gallery.