Ford Repair: 98 mustang check engine light, oxygen sensors, intake runners

Question
Dave:
98 mustang 3.8 litre, 5-speed w/ac  129,000 miles
Thanks for the good reply.
While I was waiting for your reply I pulled the codes again & wrote them down as I shold have the 1st time. They are:
P-171 too lean bank 1
p-174 too lean bank 2
p-1131 lack of H02S1 switches lean bank 1 sensor 1
p-1150 lack of H02S1 switches bank 2 sensor 1
p-1151 lack of H02S1 switches lean bank 2 sensor 1
I was thinking if the coolant was getting into the intake runners it might have contaminated the front oxygen sensors. Since I can find no external leaks I am thinking about putting in some BARS LEAK in case there might be an internal leak.
I checked for a vacuum and EVAP system leak and found none. Are there any particular points I should make sure I have checked?
The EGR valve opens and snaps back when I apply and remove vacuum. When the car is at idle if I apply vacuum it will die as the EGR opens.
The car idles fine. It does seem to be down on power just as you are letting the clutch out to accelerate from a stop in 1st gear but maybe they are all that way I don't know. Other than that it seems to run fine.
Do you think it would be worth trying to clean the EGR or can this be done successfully and what should you use to clean it?
Is there a way to check the MAF sensor?

Thanks again for helping.
Terry

Answer
If there was enough coolant leaking to damage the EGO's, there would be smoke from the exhaust.  Because the engine is running well, I would guess that the MAF Sensor is bad.  There really isn't a good test for the MAF sensor.  Sometimes you can watch the voltage stay within range while idling or driving, and the sensor is still bad.

I hope this helps,
Dave