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I have a 05 taurus running rough.

Came in with dtc p301,p302,p303,p300, p1296,p1298,p0175. vehicle had original wires and plugs. replaced spark plugs and wires and ignition coil per customers request. now vehicle runs rough and wil only idle a short while before it stalls out. I have good spark, fuel pressure was fluctuating between 30psi and 45psi. replaced fuel filter (it was also original).we have good fuel pressure no aparent vacuum leaks seems to run rich o2 sensors are high 920-950 with not much movement have checked intake and vacume lines for leaks and not seing any.

Any help is greatly appreciated. also removed maf sensor and cleaned debris from sensor. dtcs now are p1296,p1298,p300,p0175

There are 3 different 3.0 engines listed for a 2005 Taurus. Care to tell us which one this car has? 8th digit of the VIN please.

HEY THE 8TH DIGIT IS A U

Have you checked exhaust back pressure? Have you reset the adaptive memory? If both are ok id test maf.

Back pressure ok cler memory twice recheck with know god maf sensor

Clearly it's rich and we need to find out why. What are the P1296 and 98 codes? I'm not showing those for a 2005 Taurus.

Its only rich on one bank.. When u say cleared you mean adaptive memory or just codes?

Any luck?

ok so both banks are running rich. have cleared adaptive memory twice. did not have access to back pressure checker. i installed a vacume gauge to intake and at idle I have 8in of vacume. I know it should be around 18 to 20 so this engine is starved for oxygen. I removed the exhaust at the manifolds to see if vacume would be restored but it did not change the reading. all the spark plugs are black with carbon and there is a black patch behind muffler from vehicle running rich. not really sure where to go from here. I am thinking I may possibly have something internal on the engine that is damaged but when the maf sensor is unplugged and it is in default it seems to run better but the miss is still present.

1296 and 1298 are both air/fuel sensors biased/stuck rich. 1296-bank 1, 1298-bank 2. thank you again for all your help.

Everything im seeing indicates a Maf problem. What is the maf reading?

8 inches of vacuum tells me it's not breathing right. I'd be checking mechanical engine first. Compression, timing first. Backpressure test, etc.

Comp test?

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EGR valve stuck wide open ??? Intake gasket sucked in from the crankcase side ??? Camshaft out of time ??? Something wierd is amiss internally it sounds like to me.

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will be doing comp test today and will post all the data for everyone to see. when i tookthe upper plenum off i looked at the lower intake gaskets and did not see any breaks of any kind.i also did the engine running with carb cleaner around the intake and all vacume hoses but the engine never changed its performance (like when you find a leak and the engine dies or revs up). thank you again for all the help everbody.

here are the numbers im seeing on the data log while its running.
baro (kpa) 92
baro (hz) 150
dpfegr (v) 1.03
egrvr (%) 0.0
ect (F) 172
ect (v) .69
iat (f) 79
iat (v) 2.96
maf (gm/s) .84-66.81
maf (v) .53-4.68 (stays around 2.93)
sparkadv (d) 4-22 (mostly hangs out around
o2s11 (mv) .987-.992
o2s12 (mv) .957-.962-slow switch
o2s21 (mv) .987-.994
o2s22 (mv) .970-.972-slow switch
sft1 (%) 6 when cold then -28 when at operating temp
sft2 (%) 6 when cold then -28 when at operating temp
lft1 (%) 0
lft2 (%) 0

i have a feeling it is something super simple and i am just overlooking it or overthinking.

This is clearly rich. Once I've determined that mechanical engine is ok and there is no exhaust backpressure, I'd then look at fuel pressure. I believe this is an electronic returnless system, yes? So you should have fuel pressure pid in the scanner. I'd measure mechanical pressure to see if it is in spec, then compare to pid pressure. Lots of problems with fuel pump control modules on Ford. Once fuel pressure is confirmed ok, then look at fuel control. MAF, O2's etc.

ok compression test is complete. all cylinders are at 175 psi. so im going to say i have decent compression. this is a returnless system i believe. i posted fuel pressure in a previous posting. i will look at the pid and go from there. like i said its probably something simple and im just over looking it.

Don't forget backpressure. Just loosening the manifolds doesn't really cut it. You need to actually measure it. The tool screws right into the O2 hole. If you do any amount of testing, this is an essential tool.