purchased a 1989 form. firebird @114000 miles puffed little smoke when shifting. found out using 1 quart oil every 200 miles. put new valve seals in and still same thing. checked compression avg between dry 154 on avg. wet avg. 200 to 234. (not sure working correctly). all plugs seem to be normal except # 3 is oil fouled. with this low mileage the car runs great no noise, no leaks etc. there is black deposit in both exhaust pipes. if you can tell me what it could be i would appreciate any input. culd this be rings or just need the heads reworked thanks