p1538 and p1131 codes 97 Windstar

I have a 97 windstar i just picked up and im gettint the p1538 and p1131 codes.I know the p1538 is the imrc is stuck open and the p1131 is the Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1.The question i have is could the imrc cause the p1131 code?If not which o2 is the code 1131 pertaining to?I think these winnies have 4 o2's if im correct.Also how hard is it to get the imrc off and replace it?Thanks

On the 1996 through 1998 3.8L windstar, the IMRC is OPEN....and closes when you start the motor.
This is done by the intake manifold vaccum....through a vaccum line...which passes through the IMRC solenoid.

I would make sure that the IMRC in question can be manually closed.
Also....remove the vaccum line from the other actuator....and hold your finger over it.....and see if the defective side closes.
The most common failure with these is a leak in 1 actuator......which can rob the other of it's vaccum.
Often BOTH don't work.....but only 1 is defective.
In your case.....1 working and 1 not (if you have visually verified that 1 is moving and the other is not), MOST likely the one not moving is the defective one....but at the cost of the actuators.....it is worth verifying to be sure.

Also.....see if you can move the defective side manually.....just to be sure that it is not hanging up (dirt buildup inside the lower intake manifold).

When buying a replacement actuator......get ONLY the Motorcraft brand....There was a thread on here a while back of people having problems with aftermarket actuators.

I have not personally changed an actuator....so I don't have any first hand knowledge on that.

P1518 is the actuator for the FRONT bank of cylinders.

P1131 is the upstream oxygen sensor for bank ! staying lean.
This is the oxygen sensor for the REAR bank of cylinders.......BEFORE the catalytic converter.

I would try to solve the IMRC problem first.......make sure that 1 is moving (have someone start the engine while you watch the rear bank actuator....to verify that it is moving).

Then you can verify the wiring for the oxygen sensor.....the P1131 code is less common.
The oxygen sensors actually failing is also less common.
But they are easy to change....

The IMRC is not too difficult to change. A word of advice though....when you pick it up at the dealer also get the little plastic busgings. If you didn't break the original getting it off you will probably break it putting it back on. In fact, from experience I always purchase enough to replace all of them and have a couple spares. The first time I did it I thought if I was careful I could save a couple bucks but I broke one. I went back to the dealer and bought exactly how many I needed then sent one flying across the yard resulting in another trip to the dealer. The part cost less than the gas to go get it.

The part # I purchased is F5RZ-9F955-AB Bushing.

Thanks for the answers.It was very easy after i removed the alternator.I didnt replace the o2 for the p1131 code till i could see if the cel came back on.Well it did come back on and now i have p1131 and p0136.Why would this other o2 code show up now but not show up before?