I had a clutch installed the other day and the battery was disconnected for 5+ hours. After i took the car back, the idle was acting weird. It would go to to 1900 rpm and then drop down to 1500, and keeps doing that. It's been 3 days but the ecu still hasn't fixed itself yet. Is there any way to fix this on my own?

 

All you need to do is reset your ecu. It will go away.