Honda Repair: Check Engine Light, mechanic shop, honda dealership

Question
March 05: 173,000 miles: Did tune up replacement of plugs, plug wires, fuel filter, cap/rotor, replaced O2 sensor with Bosch product for 91 Accord.  Tightened, pressed all to ensure tight fits on all parts.  Drove about 1,000 miles and Check engine light came on. Replaced the o2 sensor with new part.  Drove 800 miles more.  Check Engine light came on.  Jumped the computer and counted check engine flashes: Code 43: Fuel Delivery, but that also takes in O2 sensor, and doesn't give a specific sensor location, so it could be any number of spots between the tank & the injectors.  Since I'd just replace with a new O2 sensor, I kept re-setting the computer.  Each re-set took place at a lesser and lesser mileage, until it dropped to the light coming on about 1.5 miles driving distance.  Then the symptoms took on appearance of a too lean situation.  So, I took her to a trusted mechanic shop: They recommended replacing with Honda Original O2 sensor ($198.60 + tax + special order from Honda Dealership.  YIKES!).  What other items in the Code 43 could've/should've been checked by Trusted Mechanics? I was thinking that a check would include multi-tester use to ensure resistance, current, etc., on sensors.  They DID replace the Fuel Filter I'd replaced in March. I ordered OEM part from an on-line dealer, and will replace this weekend.  Any advice?  

Answer
Jeff:
It sounds like you are the right track, I really don't have anything to add to what you are doing. You should test the sensors with a multi-tester, as should your trusted mechanic should of. The codes do not give you any more than a symptom and a shop has the equipment to test what is causing the condition. I would also be very interested to know whether the OEM part fixed the problem, please drop me a line after when you find out.
Good luck with this.
Bill