[WindstarSufferer]

So we didn't do enough research and bought a 99 Windstar SEL which we absolutely love (leather, all power, etc) except for this minor problem that is a big headache. The check engine light with codes 171 and 174 that so many of you know about. We bought it with 92K miles on it. The check engine light came on and the dealer we got it from replaced 2 of the 4 o2 sensors. Light stayed off for a while and I got 25 mpg on the way home from NC to MD. Then the light came on and the mph slowly went down to 13/22. Got the codes ran etc and its the ever so popular 171 and 174.
We had the MAF sensor replaced as the Pep Boys guy swore that's what needed to be done. It was great for our trip down to FL--once again getting nearly 25 mpg. Then after 600 miles the light came back on and the mpg went back to 22 ish.
So, how can I tell if the TSB has already been done on this vehicle? Even if it has, should I just have it performed again?
Also, can anyone email me the TSB? I guess I can always try to get it from Ford. I have a mechanic who does good work when he knows what is wrong but doesn't seem that great at diagnosing...or maybe this Windstar is to blame. Anyway, I'd like to have him do the work.

Thanks in advance.