Your spark plug wires on the drivers side of the engine are in the wrong order-you've got #7 wire on #5 cyl, # 5 wire on #6 cylinder and #6 wire on #7 cylinder-this causes crossfiring and plug fouling at low speeds and kinda erratic at other speeds-leads to fouled plugs, valve carbon build up etc, etc and sometimes backfire will blow intake port gasket which will suck in oil to intake passage--------- and California gas on early engine?? your exhaust valve seats are goneeeeeeeeeeee