97 T-bird trouble code

My check engine light came on, hooked it up to the computer and it said that the bank 1 oxygen sensors were both bad. Went ahead and replaced all 4, figure if 2 went out the other 2 aren't far behind. Then it threw codes saying that all 4 are bad. Checked Fords TSB and it says it could be a dirty injector, plugged fuel filter, pcv valve, egr valve, dip stick not seated correctly, MAF sensor, vacuum leak, etc..., has anyone had a similar problem so I know where to start.

Welcome to the forum swfordguy. If the first time it only showed 2 bad and after you replaced all 4 it showed all 4 bad then I would suspect electrical connections at the sensors. Be sure they are clean and tight. If the engine idles rough then it could be a vaccuum leak. Spray some WD-40 around all of the vaccuum line with the engine running and see if you notice a difference in the idle. Be sure to check the ones at the back of the intake because they are prone to cracking. It's easy enough to change the fuel filter and pcv valve and they should be changed periodically anyway. Pushing in the dipstick is a no-brainer. Hopefully you still have the sensors you removed. I would reinstall the 2 that weren't giving you a fault in the beginning and see what happens to the codes. Here's a link about cleaninf the MAF sensor but you do this at your own risk! http://www.stangnet.com/Tech-Articles/Cleaning-The-MAF-Sensor.html
The EGR valve may need to be removed to clean out carbon buildup but I would do that last. Good luck.

Thank you for the info, one other thing I was wondering about where the TSB said the dipstick might not be seated correctly, the timing chain cover has a leak. It started leaking about 2 monthes after the Ford garage installed new heads when the thermostat stuck and the temperature sending unit both failed at the same time. Is it possible that the leak might be the same thing as the dipstick.

I would think it would have to be a very wide gap between the cover and block which would mean you have a real bad oil leak. Have you tried tightening the cover bolts to stop the leak? If that doesn't stop the leak and it hasn't been long since the repair was done, I would take it back to the shop and have them fix it.