2005 Subaru Impreza Engine revving slightly higher

I actually submitted this problem to someone a few months ago, with no success. So if this looks familiar to you, that’s why.

My car is revving slightly higher than it used to, and it’s experiencing some sort of backflow or bubbling in the gas tank at start up. This latter part is very brief at start up, when it’s cold.

Long story short, water got in my fuel system last summer. My car lost significant power, but it turned out there was another factor contributing to the lost power as well. The primary problem was water in my fuel filter, so I had my dealer change that out (they had to replace the filter and pump, as they are housed in the same assembly). Power was almost completely restored but the engine was still revving a little higher than it was before.

I thought there might have been a little water left in my fuel system somewhere, so I dumped a bottle of dry gas (Heet) in there. That didn’t do anything, so next time I used 2 or 3 bottles. Right after doing so, I shot over to the gas station to fill up. It was upon starting the car after this fuel up that the funny backflow/squishing/bubbling sound started. There was also no improvement in power.

Later I found out the battery was dying, and that was another contributor to the lost power. So that was changed, and I believe some power was restored, but the engine is still revving higher.

Around a month ago I had the Subaru dealer drain the fuel system. I know they drained the tank and line. Is there fuel sitting in the engine or other parts when it’s off? Could they have missed it?

This week I changed out the fuel pressure regulator, just taking another shot in the dark. Just about no change in performance. It’s like the Heet is taking up space in my engine and not burning off. Does it sound like the Heet is stuck in the engine, or fuel system, somewhere?

I have $35 more for the solution.