Hi everyone I'm having issues with my 2000 Gmc Topkick with 3126 cat . Shuts off while driving sometimes go into idel other times you have to restart the engine. It will idel and high idel all day long. Till you start driving. I only owned this truck for 2 months when I bought it. It started doing this. Previous owner changed the steering column. Not sure why. I cleaned the fuel tank. blew out all the fuel lines replaced fuel filters.new heui system,ipr,icp fuel pressure regulator, Throttle positioning sensor. I pulled all the injectors. O rings look good. Getting 72 psi of fuel pressure. I'm stumped not sure what I'm missing.im not able to get a check engine light and im unable to get the obd2 to work