Just to update so maybe this can help other people - I took the car to a trans shop, and they verified that yes, I need a new clutch.
*sad* So, I'm looking at around $700 worth of work. I thought (and so did the trans shop) that it would still be ok to drive on for awhile, but no such luck, it's sitting in a parking lot down the road right now. Oi. Thanks for the help, though. Injectors was what everyone else thought it was, but I just had a new fuel pump put in not long ago, and they were cleaned then, so I had a sinking feeling it would be another big, expensive problem.