HELP!! P0171 & P0300 codes

[buddah001]

1998 transport with p0171 and p0300 codes were found from cheap hand held scanner. Where do I start?

[LMP]

P0171 System too Lean (Bank 1)
P0300 Random/Multiple Cylinder Misfire Detected

FOr complete list of generic codes, check this:
www.geocities.com/lmp4203/Malfunct.PDF
codes 1000 up may have special signification depending on auto maker, Codes 0 to 0999 are generic and similar for all.

What symptoms lead you to investigate for the codes?

[buddah001]

Van is running really rough and the service engine light is on. Need to make emmisions test.