I own a 82 300d. Runs great in the warmer weather, but once it gets below 65 degrees it has no power. Will drive good in city, once on the highway will hesitate and not go over 60 mph. Already replaced filter, any suggestions?

 

Check your glow plugs and adjust the valves. Did you replace both filters? Did you change the air filter? The car will always be a little sluggish within the first minute or two after a cold weather start, but it should quickly come out of it as the engine warms up.

 

I have replaced both fuel filters, and the air filter. It starts and runs fine, even in cold weather. Once the car is at operating temp, if i try to accelerate over 65 mph it starts to hesitate. How often should the valves be adjusted?

 

Valves should be adjusted every year. However, unless they're really out of whack or damaged they shouldn't be affecting your ability to hit your top speed that significantly. It sounds more like a fuel delivery issues.

Have you checked the flow rate to your injectors? Have you checked the injectors? Also, try blowing out the fuel line from the tank. It, or the in tank strainer, may have a partial obstruction. Also check your fuel tank is venting properly.

 

Thanks for the advice, will check the lines and tank.