Replaced t-stat and water pump and sill no heat at idle ????

Check the coolant level for the engine.

Could be a clogged heater-core, or it could be a bad thermostat. Waterpumps hardly ever fail, unless it is leaking. The pump mechanism is direct-drive, so if it is turning, it is working...
Try checking the thermostat in a pan of water, on the stove, with a thermometer to see when (IF) it opens. If it's NOT the thermostat try flushing the heater-core (buy a kit and use a garden hose).

bad water pump

check your raditor fluid it might be low that its not keeping engine cool? maybe a coolent flush and change would help if there is blockage. they have radiator flush kits at auto parts stores

one thing with fords, the catalic convertor plugs up and it over heats the motor and runs very poor and burns more fuel than the fuel station it self. you get a check engine at all?? or loss of power? burns alot of fuel? check your fan clutch/motor too
let me tell you what over heats an engine.
1 bad radiator
2 bad water pump
3 seized termostat
4 bad heads
5 plugges catalic convertor
6 engine fan not kicking in on time or at all.

Make sure your coolant levels are topped off. Now if you only get heat when the car is moving then you have a bigger problem like your water pump has gone bad. To check this, monitor the coolant level and check periodlically under your car for puddles of coolant when the car is parked for periods of time. If you return and have small puddles under the engine then it is almost 100% that your water pump has gone bad and needs to be replaced. If you dont notice those symptoms then have your t-stat checked out.

Not that big a job, to pull the t-stat and test it in hot water in the house.
If you have a candy thermometer and a large pot, suspend the stat in the water via string, heat the water and observe if the stat opens up.
If yes, the at what temp, most are between 170-190 degrees?
If not then you have at least one suspect.
You can also button up the Ford and start it up, does it still over heat without the stat?
Even with the engine cold the pump should still circulate water.
Either way the fastest method is to turn a few wrenches to get a suspect stat out to test.
If you have a cooling issue when was the last time you changed fuild and/or did a superflush of the cooling system?

May want to by higher rated T stat. Depending on region of the country you can get up to a 210 F t stat.

Did the problem start after a drain of the cooling system? Could be air in the heater core.

I took thermal stat off car again,place it in hot water till the stat open(to see if working).Place stat back in and not put the housing back on,disconnect the top hose,pored anti freeze into hose.Anti freeze started to drip out of thermal stat,as I was filling head the air was being pushed out.I could hear like a whistle,when whistle sound stopped put thermal stat housing on,hooked hoses up.did not over heat and have heat in my car now