Is the ignition suppossed to stay exactly at the 10* BTDC mark (3VZ-E) or will it fluctuate plus or minus 2 degrees? I was trying to get it to stay with the terminals jumped, but it would jump to an occasional 12* or 8* and then up to 15*. Does this indicate a bad distributor housing or something else? Ignitor? The plugs, wires, distributor cap and rotor are only about 15K miles old. I also have a pinging problem (when running premium gas), which i guess is related to the timing jumping way to 15* BTDC. Any input is greatly appreciated!!