82 300td. The heater works great.... as long as I don't drive over 50mph. Where should I look first?

Also... I think my vacuum pump is going out. Power brakes quit on me yesterday, and there's a loudish "ska ska ska ska ska ska ska" coming from the general vacuum pump area. It's a pretty easy rebuild/repair right??

Thanks for your help guys...
Chris

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'90 300SE --- 173k miles --- (Odometer just stopped working!)

'85 Cali 300D --- 193500 miles --- (Second one) Sold Nov '10

'82 300TDT --- 236,xxx miles --- (My first one) Sold July '09