2000 bonne se, giving me codes P0401 and P0420.
I have checked the EGR passage, replaced the EGR, cleaned the throttle body, inspected and fixed a couple vacuum leaks, replaced the fuel filter, did plugs and wires late last year, and the MIL is on almost constantly.
Even thought about replacing the MAP sensor after reading an article, but it is progressively getting harder to start and not throwing a MAP code, taking longer to crank before firing. Usually worse when close to closed loop temp rather than stone cold.
This, along with it needing front brakes, rear warped rotors, the blower motor making noise, valve cover leaks, A/C bleeding off during a season with no leaks I can find even with dye, and a recent problem appearing with door locks, trunk release, turn signals misbehaving, and "check body" light coming on whenever it wants to, I am pulling my hair out.

Have you replaced the Fuel Pressure Regulator and/or the Crank Position sensor?

_________________
-Car Guy Carl
"Penelope" - 2003 SLE - 247k Miles
"Sydney" - 2000 Honda S2000 - 98k miles

A/C leak may be in evaporator( hidden in dash. if he unit works, you may want to ry a sealant.
brakes are normal maintenance for cars - make sure all lug nuts a tourqed to 100/f/lbs and you wont have disk warp any more.

first try cleaning the Maf sensor.

if you have scantool that pulls live data, the MAP should be reading the same as ambiant air pressure. in your town.
check weather for barometric reading.

with key in on position, but engine off, your data should be very close to weather data: around 1 atmosphere( 100 kpa or 14.7 psi)at sea level.

if the reading is way off, the map is funky. dont give up: your almost there.

_________________
poverty forces one to do unorthodox things

2000 SSEi
past rides:
1996 SSEi
1992 GTP
1987 Grand Am

Thanks. I cleaned the MAF last year, but will try it again.
always torque my car lugs to 90, and one ton lugs to 120. I know the rear rotors are borderline turnable, but the front pads are down.
I'll check MAP readings, even though I replaced that this week too.

No, I have not.