My Chrysler Sebring is Misfiring and Slowing

Was told it was my 02 sensor which was replaced.  then they said it was possibly the sparkplugs which I admit, was over due for a tuneup.  Had the tune up done.  Engine light still comes on and starts to flash after about 30 mins of driving and slows down to crawl.  They are telling me that I need to replace the computer module as it is not giving the proper readings.  Until this year, I have not had so many issues.  I do have 150K but was told by friend that computer modules going bad is a rarity.  I am at my wits end and have already spent over 1400.00 getting a myriad of stuff done.  And I can barely drive it anywhere at this point to get a 2nd opinion.  HELP.