Chevrolet Repair: 1991 s10 4cyl running rough, piston rings, blue smoke

Question
Greetings fron peachland b.c
I have a 91 s10 4cylinder 5 speed it runs real rough changes gears smoothly lacks power on inspection under the hood  the air filter was quite dirty seamed oil soaked

Answer
HI GORD, WHEN YOU SAY THIS ENG RUNS ROUGH,, DO YOU MEAN IT SKIPS,LIKE RUNNING ON 3 CYLINDERS INSTEAD OF 4 ??  IF THIS IS THE CASE I WOULD BE LOOKING AT THE IGNITION SYSTEM,SUCH AS SPARK PLUGS,DIST-CAP, ROTOR AND IGNITION WIRES ? HAVE YOU TUNED THIS ENG LATELY OR NOT ?? THE OTHER PROBLEM THAT YOU MAY HAVE IS A WEAK IGNITION COIL. YOU SAY THAT THE AIR FILTER WAS OIL SOAKED. THIS IS NOT GOOD. COULD HAVE BAD PISTON RINGS CAUSING EXCESSIVE BLOW BY OR POSSIBLE BAD OR PLUGGED PCV VALVE. DOES THIS ENGINE USE ALOT OF OIL, BLOW BLUE SMOKE FROM EXHAUST ?? IF YES,TIME FOR A ENG OVERHAUL..  GET BACK TO ME AFTER YOU HAVE CHECKED THE ABOVE AND LET ME KNOW HOW YOU MAKE OUT. HOPE THIS GETS YOU STARTED,,TOM..