my father has a 2001 dodge ram 1500 with a 5.9(i believe) the issue is when it is diven after about 5 min. it begins to bog way down and can barely get out of its own way. and heaven forbid its on a hill. but once its over its fine untill i shut it down let it cool and restart.

i ran a code reader on it. code PO442 (minor leak in EVAP system detected) but when i researched it a little more. i found that it should not hurt drivability.

so what could be causing lack of power?

thanks in advance.