I have a 2003 VW Jetta Wagon TDI
On the interstate it drives just fine until you try to accelerate uphill and then I slowly de-accelerate.
My boyfriend thinks it’s a possible boost leak?
Sounds like a problem with the turbo. I have the same car and just had mine replaced. A painfully expensive thing to do, but cheaper than finding another car of the same quality.
I agree that there is probably something wrong with the turbo. This is a small (1.9) diesel engine and without the turbo working correctly any uphill acceleration will be slow.
You might install a turbo boost gauge so you can monitor the turbo’s performance…These used to be standard on force-fed cars…