my son just got this truck , has 130k on it runs good BUT sometimes you step on the gas and it bogs , also will now and then spudder and stall at a idle { likes like its missing } not all the time and does not give a code . i did hook up a code reader that shows what the timming is Ect . the TPS seems to stay still but the timming seems to jump around a lot { could be the tool its one of them advance auto testers } any ideas on what could make it act up now and then with no codes ? has new cap and wires

 

A fuel pump going bad maybe? Good luck!