At a loss on what to do, ready to set it on fire.

Hello, I have a 03 Subaru outback sedan. Recently it overheated because of a blown head gasket. I had another Subaru motor from my 99 Subaru legacy sedan. The legacy had a four cam motor and the outback had a 2 cam. So I used the manifold and heads off my two cam car and put them on the four cam motor and put it in my car. We had the two cam heads re worked and checked to make sure they were fine. We replaced everything from the spark plugs to the battery, basically re did the whole motor. When we got it back together it ran just fine, threw no codes and was perfect, then it started to leak antifreeze and we figured out that it probably just needed a head gasket because we loosened the head bolts to "stretch" them because they were new and didnt think about it not sealing and the gasket was a one time seal. We took the motor back out and replaced the head gasket and put it back in. We did nothing different when we put it back in. Now its like a completely different car. When you start it, it revs right up to about 3000, then revs higher and then down to about 2900, then it will rev up and settle to 2800 then rev and settle to 2700 and so on a so fourth until it gets to about 1500 or lower and it idols, but it takes over a minute to do so. If you start the car and put it right in gear it doesn't rev at all, it runs perfect. It threw 6 different codes which it never threw before. It drives down the road just fine but you don't barely even have to put your foot on the gas, it just goes like your on the gas. Today I replaced the IACV and the TPS and it didn't do a thing. I am lost on what to do. Any suggestions?