I got it, now what?

Ok, I've got my '81 300td Turbodiesel wagon back in WI. It ran great on the highway all the way home: wind and rain, 75mph, 22 mpg. It's been great for the first few days but today seemed a little pokey. I'm not one of those anal retentives that needs to tear the engine apart when I suffer a marginal decrease in perceived performance but I am wondering what I should do to the car now that it's in my possession.
What exactly makes a "tune up" on a turbo diesel? Oil change and filter, fuel filter, air filter, what else? Should I be going back in the receipts to see when the glow plugs were last changed?
thanks much,
Liesl the diesel