Here are the steps that I followed. It only got peppy when I finished the list.

Replace all filters, including the one in the fuel tank.
Replaced injectors
Set injection pump timing
Ensure valves are adjusted properly

It's not a rocket, but going up a long steep grade, it will maintain 55 mph or so. On the flat, top speed used to be 70 or so. Now I can do 85 with out the pedal to the metal.

One more thing,,, get a good running start and as one smart guy once said,,, drive it like you stole it.

JCD