VW GTI 2005 stalls on freeway

My 2005 GTI has been decelerating while I’m driving on a certain section of the freeway. It’s a steady incline for about 1/2 a mile, the altitude changes (my ears tend to pop). The car starts to decelerate, I take my foot off the pedal for a couple of seconds and then press the accelerator and it’s usually fine.

However, a couple of weeks ago it totally stalled out on the freeway, it restarted fine. I took it into the shop the next day, my mechanic is not 100% sure what the problem is, he replaced the crankshaft sensor. Turns out it’s not the source of the problem, I am still decelerating on the freeway. I had a tune-up and new battery installed a month ago, so I don’t know what the problem is. Any ideas?

Did your mechanic test the crankshaft position sensor and determine it to be faulty before he replaced it, or is he just guessing, and throwing parts at the car, hoping something will work?

When the car starts to lose speed, do you press harder on the gas pedal? You said you take your foot off the pedal, but what happens before that?

If you set the cruise control will your car maintain speed up this 1/2 mile incline?

Define “tune up.” What did they do to your GTI a month ago, besides the new battery?

Has your mechanic tested the fuel pressure? Just a wild guess, but worth checking.

Please tell us how many miles on your 2005 GTI, and which type of transmission it has. This information is very important.

I think my mechanic was just guessing about the crankshaft sensor, the car and the mechanic are new to me. It is an automatic transmission with almost 69,000 miles.

The problem happens when I start to go up the gradual incline, I’m driving like normal, with my foot on the accelerator and it starts to decelerate. Then I take my foot off and wait. And I’ve never used cruise control, but I could try.

In terms of the tune-up, they changed some spark plugs and the fuel filter. Don’t know about the fuel pressure. Thanks for your feedback.