Rough idle (check engine light) ??

Hello,
I have a 1987 Caprice with a Fuel injected 4.3 V6. The car has under 80,000 miles on it but lately it has been idleing rough and the check engine light comes on. When I'm driving the light goes out and runs perfect but when I stop somewhere it starts to idle rough and the check engine light comes back on. I read the check engine codes and it gives two codes ; O2 sensor (lean mixture and high mixture) I can also smell gas when the car is sitting and idleling, I think I can smell it through the exhaust. I dont know very much about fuel injection and I'm hopeing you guys can tell me what I need to fix this. This is my daily driver and I need to get it fixed quick any help would be great. Also my gas milege used to be 19 miles a gallon and now it is around 10 miles to a gallon!! I cant afford not to fix this!!!

Thanks,
Matt

if it's giving you the o2 sensor code ,try changing it . afterwards make sure you disconnect the battery
to reset the computer..... the o2 sensor could also explain your fuel mileage

Thanks,, I don't know what the heck I was thinking! Makes sense. O2 code,, change the O2!!


again thanks,
Matt

OK, I changed the o2 sensor ( it came out nice and easy) Now im getting check engine code for the MAP sensor / MAF sensor. The MAP cost 35 bucks, im going to change it tommorrow. The engine idles alot smoother now, but still a little sputter so I hope the MAP sensor will fix it. I HAte this emission stuff!!

Matt

I hope the gas milege goes back to normal, when i filled it today I'm getting 11 miles per gallon!