I'll try to explain this as best as I can. So I have a 1993 Subaru Impreza. When I'm driving the RPM's will jump up and down. I'll have it in drive going like 45 and the RPM's will be at around 2,000. Then they'll just jump up to around 4,000 or so. Sometimes it corrects itself and drops back down or I have to let off the gas a little. And it jumps practically no matter what speed I'm at. I don't know if this matters but it has sportshift so i can shift from 1st to 2nd to 3rd and then to drive. But when I'm in 1st, 2nd, or 3rd the RPM's dont jump at all. I've been told everything from it could be a transmission problem to it could be a throttle sensor. Any help would be greatly appreciated.