was running rough (idle).....checked codes at azone....got engine misfire.(didn't indicate which cylinder)...cleaned maf & IAC....got another code at azone... EGR flow insufficient......checked vacuum lines cleanes pvc & hose.....brought it to emissions.........their printout
p1131....P11xx manufacturef controlled fuel & air metering
P0303....cylinder 3 misfire
P0304....cylinder 4 misfire
P0171 ....system to lean (bank 1)
P0401.....egr flow insufficient
P1132...P11xx manufacturer controlled fuel and air metering............
will take anybody's educated guess into consideration....now I'm starting to obsess about this.....thanks stan
1131 and 1132 indicate tha the o2 sensors are not switching,so I'd start by changing those-unless you've very recently changed them.
Next,the 0401 is most likely the DPFE sensor needing replaced,or possibly the inlet elbow clogged from carbon deposits.
The 0303 and 0304 are cylinder misfire codes,and likely you need plugs or coils on those cylinders changed.
The 0171 code is usually from an unmetered airleak due to broken/deteriorated hoses or connections underhood,or a dirty MAF sensor.
There's your start..go from there and see what you eliminate by changing those parts-being a '98,it's likely that they're all at end of life unless they've been recently changed out for any reason.
You might want to check the rubber elbow coming off the back of the intake right up next to the firewall, if you haven't already checked/replaced it. My 97 F150 5.4L was throwing alot of similar codes... replaced all four of the O2 sensors but the engine light stayed on.... I found a thread on this site that suggested that the age and heat from the engine causes this elbow to crack and cause a vaccum leak. That turned out to be my problem.
You literally have to get up over the engine and feel with both hands for the elbow on the back side of intake next to the firewall. Mine was only holding together with part of one side of the rubber elbow. I bought the entire breather bypass system going to the passenger valve cover but only used the rubber elbow.
Check it out if you haven't already... could save you some money on the o2 sensors.