Timing is critical on a Tdi, more so than the fuelling settings on the pump itself. A 3/8" (9.5mm) drill bit works well as a timing pump locking tool, and you can then visually inspect the flywheel locking slot through the tapping in the bottom of the flywheel casing.
People tend to forget that injectors clog and wear. I think their replacement interval is 72,000 miles, though I may be out on that figure. They do, however, have a replacement schedule due to wear of the nozzle and pin and need more frequent cleaning to get rid of coking deposits.