1990 Toyota Camry Timing

I have no power after setting the timming. I followed the instructions on the lable under the hood. When I insert the jumper into the connector like the lable says, the RPM's go way down and the timing was set at 10 BTC. I set it to 0 BTC, pulled out the jumper, the RPM's went back up but the timing said @10~15 BTC and there is no power when driving.