I have a 98 jetta tdi that I recently purchased non running from a friend. I was told it ran until it sat for a few months and then he couldn't get it started and got frustrated and sold it to me. I finally got the pump all primed and the car will now start and idle with the initial assistance of starting fluid. Once idling the glow plug light continues to flash and is followed by a constant cel light. The engine won't take throttle over 2k rpm and it takes a lot of feathering to get it up to that point. I tested for voltage between the two leads of the glow plug harness. not sure if there should be voltage there or not, but there is no voltage between the two leads. The 50 amp glowplug fuse is good. I'm new to these engines and I'm not sure of the next route I should take. VCDS is being purchased in the near future.