The other codes were for the ACT sensor, which you replaced, the MAF, which you said tested good, and that it's wires looked good, and the fuel pump circuit, which you serviced with a new relay, and by checking the wiring. Unless those codes come up as current, there is no way to determine the source of them, other than what you've already done. The codes that are current are 41 & 91, so those are the only codes we have to work with. If your mechanic says the O2 sensors and wiring are good, then that leaves fuel pressure or a vacuum leak. You said the fuel pressure tested okay, which leaves a vacuum leak. A vacuum leak would create a high idle that wouldn't change much when you created a new vacuum leak. You said you inspected the vacuum hoses, and didn't find any problems. You have eliminated all of the possibilities.
The reason why I suspect the problem may be in the O2 sensors or their wiring is because the spark plugs didn't read lean. If the system was lean, from either a vacuum leak or a lack of fuel, your spark plugs would be bright white, but they weren't. That makes me think that things are fine, but the O2 sensor circuit thinks, for whatever reason, that things are not fine. Odds are you have a bad ground contact somewhere.
My recommendation is to go to your mechanic, and have him diagnose it for you. I really don't know what else to tell you to do. According to you, you've passed all the tests.
Take care,
~Chris
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