choking problem...where do i start?

my bro has a problem with his car. i don't know what car it is, i believe it is a general problem applies to any car. it chokes a little when idle or put in gears(what gears? doesn't really matter!!). and also chokes a little bit when crusing. if it chokes too bad, the car just die. the car has never been modified, stocks and old!!

i think this probably indicates fuel system problems.
1/O2 sensor
2/MAP sensor
3/fuel pressure(or fuel filter clogged)

all i know is that car probably doeson't have a working O2 sensor. but my bro insist me to prove that. any know how to check a O2 sensor?


or any other problems i should look into this matter?
any feedback on approaches and procedure are great!!

thanks,

As far as I know the bad O2 sensor will cause the check engine light to come on. I would start with regular maintenance: spark plugs, wires, distributor cap.

Sam

yep! just found out that dist. cap's 4th wire is burn pretty bad. thanks for the pointers, good job team...