OK, I got a stumper. I've been gone all summer, so I haven't been able to work on this, but I'll be back next week, so if y'all can offer any advice I'll be able to try it when I get back. 2001 Golf, about 165K miles, 5 Speed. I started having this problem a few months ago, but it steadily got worse and worse. Basicly, when the weather is HOT, not cold, the car won't start. Moreover, when I start it in the morning, she fires right up, but if I drive for a while, then park the car, then come back after a few minutes, bubkis. The engine turns over easily, the battery is about 6 months old. I do get a regular CEL, but it says it's the coolant glow plug intermittent, which in 90-degree weather, shouldn't be giving me any grief. I've checked the anti-shudder valve, it's working properly. The folks in the Portland Diesel Fuel Injection told me to remove the pin from the cut-off solenoid, but there is no change in behavior. My last thought is to replace the fuel temp sender in the IP, does this sound like a good move? Any other ideas? I have a few bubbles in the fuel line, but nothing out of the ordinary. Please let me know if y'all have any ideas.