Just bought a 04 1500 w/hemi 156k miles. The only thing I can see done to the truck is someone pulled cats off and just clipped wire to o2 sensors (only 1 code for o2 is popping up). Main issue is about 1 out of 10 times the truck won't start. I can hear the fuel pump running each time but it will just crank. Yes, fuel level is good...turn key all the way back...sometimes it will start and sometimes it won't. Truck will also sometimes die while at idle.

 

Whenever you buy something used with that kind of mileage, there are a few things you need to do

check brake pad life
flush brake lines with new DOT3 or 4
flush power steer with fresh ATF
clean the throttle body
replace spark plugs
replace air filter
replace O2 sensors
change oil/filter
do a coolant flush
change transmission oil/filter
change differential oils
it probably needs new hoses and a belt