code 84 just means the engine power has been reduced. the procedure is the same as every code, follow the repair manual trouble tree. this site is for scanner hardware and software issues. there will be codes stored in the engine computer and perhaps in other ecu as well, engine power reduction its do to any powertrain issue (engine,transmission,abs). questions like this are allover the forum and I really don't know why people expect a fix. a scanner alone does not fix cars, knowledge and repair information is very much needed. call a tech in your area and pay for a good diagnostic or replace every module and sensor and wiring harness  on the vehicle until you get it fixed.

 sorry buddy, I think I overdid it a bit here, maybe I drank too much and took it out on you. check for codes on the ecm,tcm and abs, you will find your answer there for sure.