I'm wondering how badly leaky headers could mess up the TBI system due to corrupt O2 readings? This is just a theory, but my system seems to always want more fuel at idle and barely accelerates when cold. My theory is that maybe the headers aren't tight when cold, so some air is getting in. I have no other reason to suspect this though; there is no noise from the headers like a bad leak. Is this plausible?

 

If you dont hear a leak, then I would look elsewhere for the problem. Like weak fuel pressure.

 

But why would my fuel pressure get better once the vehicle is warmed up?

 

It doesn't even use the O2 sensor when it's cold.

 

The bad time is after it goes closed loop, before it is fully heated up. And my O2 sensor is heated.

 

No heat to TBI unit? Thermac? Fuel not atomizing properly?

 

Have all the factory stuff.

 

Does it still work?

What's your coolant temperature like while it's misbehaving?

 

Yeah, I think it works. The thing runs okay, not great, until it goes closed loop, then it won't accelerate for anything (stumbling, etc.) until around the time the thermostat opens. I can't remember what that is in degrees, but I can see it on my temp gauge because of the sudden slight drop when it opens.