Just a suggestion but have you looked into the ability of any of your local repair shops to help you? Any shop that has a L1 certified tech will likely have a gas analyzer and one of the best values on the market for a shop today is the OTC Genysis scan tool with the gas pack which has a 5 gas anylizer, calculates air fuel ratio, and displays exhaust temp, which that combination is going to actually tell you WAY more than any wide band on the market IF your operator knows how to read the data. Because it is a portable scan tool based unit you can actually put the probe in the tail pipe and take the car for a test drive (I do it all the time) and it records the data which can even be printed as a graph. May be worth a shot. I even have one and my shop sells tires (which not trying to plug Firestone, but most Firestone stores should now have these kits and someone who knows how to use them if that helps you any and the $100.00 or less that they charge you to get you that data is a lot less than a wideband setup).
