Folks

Will a main pump fail over time, i.e. get weaker and show poor performance, or does it just drop-dead fail? Same question for fuel pressure regulator.

I'm almost completely certain that I've no vacuum leaks on the air intake. Yet when I step on the gas, especially going uphill, my power hits a limit despite the high turbo boost. I sense a lurching or intermittency in the ignition under this load. I replaced the in-tank pre-pump just this past fall. Driving the car for several days with a dead pre-pump I know strained the main pump, it's very loud now.

I'd like to get some sense of the probability of either of these two parts being the culprit before I spend the cash.

Thanks for any help and insights.