I just purchased an 89 prelude SI. near the end of abt a 25-30 mile drive, when i come out of gear the revs stay around 3 grand. i pedal the throttle and the motor chokes down, sometimes cutting off but sometimes i can gas it and keep the motor alive. It will crank right back up but still idle around 12-1500 rpm. When it happens i hear a sound like air escaping. I’m assuming a vacuum leak but it doesn’t happen all the time. My line of thinking is if i had a hole or popped hose, the problem would be continuous. Any ideas on where to start?