I purchased my 2007 WRX with 100k miles on it back in August and it ran fine for the first few months. Then I started to notice a slight hesitation when accelerating, like its not getting enough fuel or a belt is slipping or something(didnt matter if I was boosting or not). Someone told me that it might be a problem with crappy oil used by the dealership, and to try some different oil, and put Seafoam in it. So I had the oil changed using Royal Purple, and added a can of Seafoam to a fresh tank. This made no difference, and maybe a month later the car started having idle issues too. Usually the car idles at about 500 rpm at a stop, but sometimes it will all the sudden start jumping from 500 to about 1500 rpm, then back to 500 , and it acts like it's going to stall(lights dimming/ect), and on a few occasions it has died on me while doing this. The idle problem only happens after the car is warmed up(driven for at least 15 mins or more), and it won't do it if it's too cold outside(below 35 degrees or so). Someone else told me it might be a good idea to clean the MAF sensor, I did this, and it did not help either. So a few weeks ago, I took it to an independent Subaru shop, that only deals with Subaru's, and asked them to diagnose it. They said it could be all kinds of things, and they aren't sure whats wrong exactly because it's not throwing any check engine lights or codes. They cleaned out the throttle body to see if that helps, for free, and said if it becomes worse to bring it back. I'm irritated at this point, because it already is "worse" in my opinion, that's why I brought it in! So today I took it to a different independent Subaru shop that said they can help over the phone, after keeping my car for half the day they said they test drove it and didn't notice any hesitation or idle issue, and that the car is due for a re-flash of the computer or something to that effect. So i'm having them do that at a cost of $200. My question is, has anyone had this issue before or have a good idea what might be wrong? Do you think that this re-flash of the computer is going to help, or did I just drop more $ trying to fix these issues for no reason? I really love my Subaru, and just want it to work right, without paying thousands of dollars to a dealership for repairs....please advise. By the way, the car is completely stock, and always has been.