Focus ZX3 2.0 DOHC ZETEC

• Manual transmission
• 50,000 miles

About 30,000 miles into ownership, I descovered that the engine does not want to idle down properly at times. I have a manual tranny for a reason---engine breaking power. But what good does it do to let off the gas when the engine is not slowing down, to slow the car down? The problem had gotten more pronounced last year before my 3yr/36k warranty expired, so I decided to send it into a Ford dealership to get it checked. Over the phone, they first told me that they were probably going to re-flash the computer. Then, a couple of days later they called me and said they didn't have the equipment at the dealership to do a reflash on the newer system that Ford is using, so I would have to wait a couple days max. Then, once the equipment had arrived, they decided that this wasn't the problem and said the TPS (throttle position sensor) was out of wack. Then, they called me back and said the EGR unit (exhaust gas recirculation) was bad. Then, they called me and said that they changed their mind and were going to replace the throttle body unit. So after all that, they replaced the throttle body with a new one free of charge. I used one of their SUV's to drive to work a couple days.... no big deal. So then there was no more idling problems that year. But this year is the same reocurring problem which leads me to believe it's not the throttle body. The idle problem only occurs after the engine is mostly up to full temperature and has been driven at least 4 miles in warmer weather (idle problem doesn't occur below 60 deg weather). I'll go to slow for a stoplight and let of the gas....... and the engine almost doesn't do anything, it just sort of floats where I left the gas. So I have to force it to slow with the brakes and wherever I slow it to, it pretty much stays, except it "floats" around a bit. When I roll to a stop with the clutch in and foot on the brake, the engine sort of spools up to about 2,200-2,600 rpm and floats around a little bit. If it's a hot day, it will never idle down below 2,200 rpm even after sitting still for a long time. "Eventually" it settles down to the normal 700ish rpm. Really anoying problem. I like manual transmissions for their reliability and simplicity, but this is worse than a slushy automatic when I let off the gas and get no pull-down from the engine.