I have an 81 300D. In general it runs well. I was recently backpacking and parked the car at 10,100 Feet (my home is around 5000ft here in Utah). After 2 says, I came back to the car and it cranked until the battery died. I got my friend to jump me and it took another 5 minutes of cranking before the engine would turn over.

One thing I noticed is that at first it sounds like nothing is firing. Then you can hear a few cylinders firing, but they stop. If I kill the crank and let it sit a few seconds, more fire, then drop out. Sit again, even more, until it starts.

I haven't really checked anything yet but was wondering if anything sounds suspicious? I was planning on checking the glow plugs first and proceeding from there.

On a normal warm day it takes the car about 10 seconds to start after its sat all night. Once the engine is warm it starts instantly.