When I'm driving and take my foot off the accelerator the car doesn't stop revving for half a second or so. Noticed it when I started putting the clutch in to change gears and it would rev up. Has been happening the past month roughly, would happen for 10 minutes or briefly and go away though, not sure if it was related but would (while car was off) fully depress and let go of the accelerator a few times and problem would stop majority of the time. Now has become a consistent thing every time I drive it and I have to let off accel and wait a second before putting the clutch in. This a warped or frayed throttle cable? If that's the case was wondering if the S13/S14 throttle cables are the same as the S15 part. Or is it something else?