2000 Subaru Legacy Engine races when cold

My Subaru has been in the shop for numerous repairs in the last couple months, including cooling problems, bad starter, and power steering fluid leak. Since my mechanic put in "stop leak" for the power steering fluid leak last week, when I start the engine when it's cold it races for a few seconds (it's pretty loud), then comes back down, but still seems to idle high until it warms up. If I stop somewhere and start it again within a short period of time, it doesn't do this. This is all new since I had it in for the power steering fluid leak. I don't want to take my car back in for repairs again so soon, so thought I'd see if this was something serious.