One thing I forgot to mention is that once the engine is hot and I turn off the ignition the engine keeps running for for a few seconds (dieseling). That's why I thought the problem was timing. But as I said before I already tried adjusting the timing...
The reason why I made a new mark on the balancer was because when I tried to check timing the mark on the balancer was way off so I thought maybe the outer balancer ring had slipped. But now I know it didn't as the new mark is also way off at idle, about 30* advanced.