jrruta,
Try finding a factory service manual at
www.ebaymotors.com I found one there for my truck for only $35.00. Factory original service manuals are unbeaten with information. Sorry I'm a carb guru. The oxygen sensor is definate if it has never been replaced. I change mine on my FI truck every 30,000 miles. Check for fouled plugs too. A foul plug will give you hell during the winter season. A good TBI cleaner should be used if you have not done that too. When was the last time you changed the fuel filter? Give her a good tune up too.