Once you get to WOT per the TPS (which is a TPS reading of ~3.7 volts if your baseline is around 1.0 volt) the input from the O2's (on a fox) are ignored.
if your o2 sensors are bad your check engine light should be illuminated and you need to pull codes and post codes recieved and/or test o2 sensors a repair manual will advise you how to test o2 sensors with a digital voltmeter the manual can be purchased at any parts store and you can purchase a voltmeter at wal-mart for $20
Dump the codes and see what the computer says is wrong…
Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.
IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.
Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.
Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.
For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.
In that case, I would provide more ancillary information about the issue. Also, if your username is indicative of your car, a list of modifications will be useful.
347
8.5:1 compression
performer heads
bbk shortys 1 5/8
dynomax cat back with h pipe
trick flow street heat intake
70 mm BBK TB
24 lb injectors
soon to come, nitrous works nitrous plate kit
AOD with 3000 stall
C&L mass air meter
Cold Air Kit (cheapo)
Code 85 is a Canister Purge (CANP) circuit problem....do you have it disconnected?....it could be in a not-normal open position causing gas fumes to be continously drawn into the TB, if connected. If it's disconnected, that's the reason for that code....have you run a KOER self-test?...it would also help getting the results of that self-test. LUK
My first guess is TPS, my second would be a MAF issue. The MAF would usually shoot a code, but with the TPS, it's hard for the ECU to detect it unless it is completly open or shorted. Do a sweep, read the signal voltage, it should be right under 1V (.9xx) and as you open the throttle there should be a smooth increase in voltage until about 4.3-4.5V at WOT. Any spikes or dips will tell you that there is a problem. MAF's will do all kinds of crap if just a little dirt gets on the sensor wires.