I have an 89 buick lesabre with a 3.8L engine.is there someone who can tell me which part of the emission system controls the (HC(ppm),CO(%) ) thank you

Everything is interrelated. There could be one part of the system that has failed or it could be a whole bunch of little things. If you do not know much about cars, then I would suggest to save yourself a lot of money to simply take it to a GM dealer and pay them to hook it up and give you a list of problems. Otherwise it is hit and miss.

Is there a code stored in the computer? Checking that out might help point you in the right direction.