Hello,

I have a 97 Taurus 3.0l 12v Vin: U with 123,000 miles

I am not a expert on this engine so here is what has been done with various results:

History: I bought car at 108k miles and had been serviced at Ford dealer since new.

At 108K miles ago Bosch or Champion spark plugs ( OEM type ) and mag core wire set.
car was fine. ( Also PCV valve and fuel filter in June of 2005.



Started rough idle few weeks ago and rev up and down idle - NO CEL - but 1 code about unable to check rear O2 sensors
It runs fine for a few min and then there is a slight mis or roughness that did not happen before a few weeks ago.

3 bottles of fuel injector cleaner made quite a change about 90% better but not 100% like before.

Changed: 1. IAC ( Idle Air control valve) from Kragen auto.- fixed rev up and down idle
2. Replaced all 6 injectors- ( reman. from kragen.com Auto parts) ran smooth for a week but still had a slight rough idle.
3. 4 Oxygen sensors ( Bosch) 2 pre cat and 2 post cat - due to code
4. Changed coil ( from junk yard) made no improvement.

So what is left to do? At this point I may be forced to go to Ford and pay the $110 diagnostic fee or a place like Pepboys who want $80.




I have like 5 junk yards near me so I leaned how to change the injectors on a wreck before working on mine and can get any parts to swap like a coil or sensor.


My plans are to wait for your advice
1. Should I put OEM spark plugs and wires awsf32pp plugs and OEM motorcraft wires?


Any advice is welcome,
Thanks

 

I would have ran the test way before spending all of that money on parts, I'm curious to see what the problem is.