308FI starts up,runs fine, then lugs

2 things to start with.
Air Aux Valve. It should have a high idle for the first few minutes at 1800-2200 rpm. I think your car also has a Cold Start Air Valve (not the blue harnessed injector). Check that too.

Then if both check out test your fuel pressures, cold control, warm control, system pressure and while you are there rest pressure.
As it could be in your warm up regulator.

IME a rough and bogging idle is the WUR when the car was running well before.

 

I'd also check the electrical connections to your coils. My coils became really corroded which caused an incomplete burn on one of the banks.

When things like this pop up, always check the plugs for color and condition...they can shed a lot of light on what's happening inside the motor.

 

Well, if they're soaked with fuel, it sounds like either an ignition problem, or the ECU is commanding a lot of fuel for some reason(perhaps a sensor is giving it wacky readings). I'd replace the plugs, and check the coil/s and go from there.



-DC

 

With my experience in the past, I completely agree with Forza1. This is an electrical issue. Something is not causing a complete burn (hot enough spark) at the plug. Go over ALL of the electrical connections from the distributor, ECU, coils, etc. You'll find it.

If you let the car run too long in that condition, the unburnt fuel will collect in the muffler and will get super hot!

 

...or the unburned fuel will ignite in the already hot catalytic converter, which can (and will) catch on fire. (Tip: If your "SLOW DOWN" light ever comes on, pull over immediately and tow the car to a shop. Been there, done that.)


--Mike