1994 Toyota 4Runner Engine Runs poorly

3.0 (6)j runs poorly. Smog test show excessive HC, but also found timing was way advance from BTDC of 10 DEG to 27 Deg. :Put a timing light on the vehicle and attempted to adjust the timing. I could not retard the distributor enough to get to stock settings. Ran out of rotation. Best I could do was 12 Deg. Car runs but has lack of power and rough idle. Also during the timing process the timing mark on the pulley at times was erratic and would jump down to 10 degs on its own for a few seconds and then jump way up and settle. I have checked for vaccuum, replaced all wires, plugs, cap rotor checked air gap etc. Could the bad timing cause excess HC emissions, and would there be a cause for the timing to be so far out and unadjustable.