I have a 99 pont Bonn, 3800 II, no supercharge with 230k.
Having ruff starts, sparatic idle, then would run fine.
so I replaced plugs, wires, coil paks,fuel injectors, fuel regulator, fuel filter.
This got rid of engine code, misfire cyl 5
still ruff starts, if i held gas down a little, it would start right up, but wouldnt start if I just turned key, had to give it gas.
Engine light came on, took to autozone, gave 1404, which means their scanner couldnt diagnose the problem.
After reading your posts changed the Idler Air Contrl Valve, in process broke off both screw heads holding it on, I even bought the correct star tip to get it off. be careful. Had to pull the whole intake out, drill out holes.
But it worked, starts right up, and idles fine,
Thanks for great advice!!