[fogged306]

Well the 2.5v at WOT isn't right. You should be at least 2.71v above whatever your reading is with the plate closed and no more than 5v at WOT. If you've got 5v at the vref, then I would check the sig return. It will test like a ground. I forgot to plug my TPS back in once and took the car out for a test run. It ran all kinds of strange, stalled, and then wouldn't start back up again. In your case, being inside the tolerance at idle, this may be a non issue to your no start problem you just had, but maybe not. And it will definitely cause driveability issues the way it is now.

The ECT/ACT question is a good question. I can't tell you either way. If I were to guess, I would have to assume that the computer wouldn't work that way because it would throw those codes every time you started the car until it got to temp. While I believe that's not the case, I'm not 100% on it but I've seen stranger shit happen with factory stuff before so who knows.

The VSS code shouldn't have anything to do with your car being to idle. The only function it has that I know of is to keep RPM's up (in a manual car) when the clutch is pushed in and the car is moving above a certain speed to help power steering and brakes. I'm sure it's tied in to the cruise unit also.

That 41 could give you some driveability trouble too, Easy way to tell if it's the o2 or the wiring is to switch the o2 sensors. If that 41 changes to a 91 then your o2 is shot. If you still have a 41 then you have a problem with the wiring to that o2 sensor.

This is that whole website where i got the diagram. There's tons of really good info on there and some pretty good reads on the EEC and the logic it uses, which is good knowledge to have when you're trying to figure out an issue like this. Mustang FAQ - Wiring & Engine Info

Another thing you can check is your EEC itself. Sometimes the capacitors crap out and can give you strange results. Pull the case and look for black deposits on the circuit board directly underneath the caps.

[OmniEquipped]

Excellent suggestions. I don't think I've tested TPS return like a ground. So I test for continuity with the key off?

Also, I'll swap the o2's and see what code pops up. Hopefully I'll get a chance to do this within the next day or so and I'll post results. I do appreciate the help.

[fogged306]

No problem. I'm on a job at the moment and it involves me guarding things for the next 14hrs in a room where nobody will ever walk into. So this is keeping me entertained, hah.

If you're using a multimeter, I'm not sure if it would test continuity to actual ground or not. It's a ground circuit but I think it's an isolated circuit so you may or may not get continuity. I've only my power probe to test sig return line on my fox.. being an isolated circuit, I wouldn't use a regular test light though. It's probably not even a smart idea to use a power probe, lol. But I've only blown up one coil pack in like the 7 yrs I've been using them on computer equipment so I'm pretty confident they're computer safe-ish.

Another way would be to see if you're getting 5v between the sig return and the vref.

[OmniEquipped]

Progress: I was able to fix the TPS portion of the problem. Turned out to be a sensor issue as opposed to wiring (thank God). It's dead nuts .98 at closed throttle and 4.1 at WOT....finally. It runs better now, but still not perfect. The next step (when I get time to get back on it) is to test the o2's. I'm also going to test the voltage and ground at the MAP sensor. The MAP, coolant temp sensor, and air temp sensor are all original to the engine, so I may go ahead and replace them altogether. Then I'll see how it drives and run codes again. Feels like I'm heading in the right direction.