Sometimes on my car on the highway, the car sort of cuts out for just a quick second, then is fine. Maybe 30 minutes later, same thing. I thought maybe the turbo was going.

Today, I was driving in the moutains on a 12 hour drive to PA, and had trouble going up some of the steeper and longer inclines! I've driven those roads many times with no problems, and today, the car just couldn't do it. The roads are 60-70 mph, and (cough) 40 mph is all I could do! The car was just dying.

Again, I thought it must be the turbo going, but I called my mechanic, he said it sounded like a fuel issue, maybe a clogged injector or something

After the high part of the mountains, already doing 40 mph, I was going on a slight DOWNHILL, and the car was having trouble accelerating! So I thought, can't be the turbo. Must be a fuel issue after all. If I REALLY step down on the pedal, it will then accelerate more like it normally does, but there's obviously something wrong with the car.

I changed the pre-filter and main filter a week ago (the engine cutting in and out was happening prior to that), and cleaned the injectors directly 2 years ago.

Any other guesses or possible solutions?

1991 300d 175k