The other week, I went to work, put my 2003 vibe base (115,000 miles) in park, and the engine idle shot up to 1,500 rpms and would not come back down! I had no idea what was going on. So I took it to my local meineke and they told me a few things. 1. My computer had not completed 4 of it's loops tests, though he only told me evap, oxygen sensor, and catalyst. He said without them completing, he wasn't able to determine fully what it could be that is causing the issue. He offered to try an entire engine cleaning service which i had him perform. It did need done as the engine is far smoother than it had been previously however my issue remains. when i'm driving around, it seems that the engine rpms are higher than they should be at low speeds and high speeds alike.
The other thing he recommended trying was iacv but he couldn't guarantee that would fix the issue either and for 623 bucks, I opted to come here first to get some opinions of what to do. It is currently 87 degrees outside so this is not a cold start issue. when the car starts up, it goes to about 1100rpms and, once warm, drops down to about 1000 rpms while still in park (as far as i know, this is still slightly high). Once i drive around and come back and the engine is nice and warmed up (regardless of amount of time driving), I put it in park and it just shoots up to 1500 and stays there. When my ac and stuff are on it drops (while still in park) to about 1100 or 1200 rpms. my gas mileage is really bad as well.
Meineke guy also told me that he didn't detect any vaccuum leaks. I also did a listening check for them and didn't hear any under the hood.
The guy at meineke also asked if i had just replaced the battery and reset the computer since the loops weren't tripped yet. I told him the battery was last year and the alternator is original. I only drive this car back and forth to work about 25 miles total a day through mostly back roads (though some of them hit 50 mph speed limits). I had filled this card up to full and in one of those trips since this incident, i was down 1/4 of a tank of gas! So basically 4 gallons in 25 miles (give or take)!
What I've done so far. Checked air filter, great. Cleaned maf, didn't even need it. Oem spark plugs replaced about 20k miles ago with new oems. cleaned pcv valve, barely dirty. Repalced intake manifold gasket long ago with the updated one from toyota that solved my check engine light issues in cold starts (very common issue).
It's also worth noting that I take good care of the car, coolant, transmission, brake fluid, rotations, belts and oil changes all done when they are supposed to be or sooner. There is/has been no check engine light since this issue started last week.
So now I have some questions:
1. Should I have them do an iacv at meineke or should I attempt it?
2. Is there a link with pics to doing the iacv?
3. Is the iacv the most likely issue or could it be my ecu needs an update?
4. Have any of you experienced this exactly issue?
Please help point me in the right direction. I really don't have the cash to just throw money at it and guess what the issue is. Thanks in advance to anyone who responds.