For the past couple of days my N/A '86 MT has beed acting a little weird. I started it up the other night and it warmed up at 2k like usual (I always give it a little gas cause sometimes it dies and sometimes it doesn't) but this time when I gave it gas the tach went to 3k and stayed! I thought maybe my throttle cable got jammed but it wasn't. The car was pouring out smoke from revving so high while being cold. I shut it off then turned it back on, it went to 2k then started revving itself from 2.1k to 2.4k back and forth. It only does it at certain times now but I wanna get it back to normal. Any advice?