I was driving my Blobeye Wagon WRX (EJ205 non-modified) today and it had been driving perfectly fine until after an hour or so went I went for an overtake from about 45mph to 60mph when I got a sudden loss of power. The engine kept running, but was really struggling along. I could then barely get it up to 35mph, so had to encourage the car I'd just overtaken to overtake me back (the embarrassment of i!). I pulled over and let it rest for 20 mins, then started driving again, but the power was terrible and I could barely get to 40mph, so I pulled over again. This time I called out recovery which took about an hour to arrive. While waiting I plugged in my OBD diag tool to check for error codes, but it was all clear. There were no obvious visible problems with the engine. When the recovery man arrived he couldn't see anything awry. He then took it out for a quick drive, and said there was plenty of power and boost, but a little hesitant when going for it. So he suggested I carried on driving. It then drove much better with enough power to get me home without a problem (an hour drive), though I didn't do any hard acceleration. So something had 'cured' while I was waiting.

I've had the occasional cut in power when accelerating hard before, but it's always got back to normal after a few seconds. But this felt like something had seriously cut the power. Any ideas what to check for, or anyone experienced the same?

 

Fuel pump

 

Would a dodgy fuel pump appear to sort itself out after an hour or so rest? Does the ECU cut the power when it thinks the fuel pump isn't delivering properly? The sudden change from the engine running fine to very little power did seem odd.
There's no harm in me changing the pump, it could still be the original one.

 

They become intermittent before they give up and on boost they can't provide enough fuel and run lean.
Then you can melt things.

 

I replaced the fuel pump with a new one (went for a Walbro 255), and didn't really notice any difference. However, the car continued to feel a bit slugglsh, but not completely losing power; so something else is clearly wrong with it.
Due to an oil leak from the rear of the engine which I've meaning to fix for ages, I got round to removing the engine today. I did a compression check while doing that, and found that cylinder 1 was only at 130, while the others were around 160-165. So that could hint at least cause for the poor running.

 

Joe Biden guess was wrong as usuall.
130psi is not bad but should be equal on all cylinders