These motors are pretty reliable, but there is a bit of work that must be done to prevent the common problems. Nothing too serious and any weekend warrior (myself included) can handle it.
Do a search for posts by me "TomS" and search for "VST" and you will find a few different threads where I have rambled on about the common maintenance stuff.
Items you should have checked:
T-stats, pressure control valve, water pump
Oil control rod adjustment
TPS (Throttle Position Sensor)
O2 Density Sensor
VST Filter
-- Tom