my freinds 98 gsr is missing or bogging when he steps on the gas. he has new fuel filter, plugs, wire and cap and rotor looks good. his catalatic coverter is loose inside so when u rev up, it rattles inside and i thought it could be plugged up and causing the problem. it all started when one day his car died and when it started back up after 1 week with no clue why. could it be the ignition moduel, watered fuel. any help please.