I recently took off my intake manifold and preformed an engine flush on my 83 280zx turbo. After doing this my engine began to idle at 2000 rpm and rev when warmed up. I ended up loosing the cruise control cable and was able to drop the idle. Now the engine starts up and idles about 500 to 600, without revving. After the engine warms up, when the temperature gauge shows 4 or 5 bars, the engine begins to rev from about 800 to 1200. The revving is systematic. The engine also starts up right away. I checked the grounding cables and everything is fine. I also checked the throttle and it moved freely. I don't think that there are any air leaks because the revving is systematic. It feels like the warming up settings and the idling settings some how got switched, but I don't know vw to switch them back. Thanks.