About a month ago I asked for help diagnosing my car, it was hesitating and losing power when on the highway usually in forth gear, then when I would downshift to third and get the rpms up it would run fine again. It would do this for maybe five or ten minutes and then go away sometimes for a couple of days. I was told to change the fuel filters and then see if it got better. Someone said the carb is probably toast.

I changed the fuel filter under the hood but not the one under the car (it was changed 14 K ago). Now it doesn't do the hesistating on the highway anymore. But I have a different maybe related problem. It starts fine and its cold idle is fine, usually its warm idle is good for a couple minutes. Once its all the way warmed up the idle falls from about 800 rpms to maybe 400-500 rpms barley running and sometimes dying. If you get on the gas it runs fine and driving around it runs great, it just doesn't want to idle when warm? I tried fiddling with the idle speed adjuster but the idle just jumps from barley running to about 1100 rpm. I'm going to change the fuel filter under the car to see if this helps but do you guys have other ideas? Its a hitachi carb and has about 168K.

i'd clean the carb

sounds like a similar problem to mine..... i think my carb is toast

So I cleaned the carb and changed both fuel filters, seemed to help a little. But it still wants to die sometimes when idling, other times it idles fine. Still drives good. I have know idea what to do now. What are my options with regards to carbs? I think my brother might have a hitachi I can maybe use.