When going down the road I loose heat & when idling I have hot air & I've replaced the thermostat 5 time.Where do I go next?

are you losing any coolant at all? if your engine is running at optimal temperature not over heating or running too cool. i would suggest taking a look at / flushing your heater core... if your heater core gets clogged up it will have a hard time circulating antifreeze or if its leaking it will not get hot. Assuming you are not loosing any coolant i would highly suggest flushing your heater core. there are many places that do this and it shouldn't be too overly expensive however if you are a do it yourself-er here is a video that may help you along. you will be looking for 2 hoses almost side by side going to the passenger side of the fire wall typically closer to the floor. and remember to back flush. the hotter line is input and cooler one is output. reverse them for your flush. good luck and let me know of your results :) http://www.youtube.com/watch?v=dcL_0TWeZJY