drewt

Well my truck (98 f150 4.6L) decided to randomly start running very rough, especially under load e.g. When I put it in drive or reverse. the rpms stay steady at around 800 in park or N. Under load, it drops down to 500 or so before accelerating. around 1500-2k it runs very rough. after changing my pcv valve, i had it diagnosed. they said bank 1 is lean. and the diagnostic was reading that 2 of my o2 sensors {upstream} weren't working right. and he said i'd have to replace all 4. which i feel is bogus. any ideas?? should I change them? or have it just further checked for vacuum leaks? I don't want to have to pay over 200 for o2 sensors if I don't have to. thanks guys. oh also, my egr solenoid buzzes after shut down. related? update- just drove it, and after warming up, it ran much better all of a sudden. could this be because the 02 sensors got to temp late?