My 4L SOHC set codes & failed state inspection

Please help. My '97 4L SOHC set Powertrain codes 442, 420 and 174. Not havng a lot of time or $$$ right now I tried clearing them to pass the new OBDII inpection but then failed anyway - I have to drive it 200 miles so it can reset the codes and they gave me ten days to do that.

According to the book, the codes mean the following:

442 - EVAP small leak detected 420 - Catalytic system bank 1 efficiency too low 174 - System adaptive fuel too lean on bank 2

It idles a little rough when warm; during winter it would race, then bog, then race again during warmup. I have heard about the plastic intake/gasket issue, and have even bought the gaskets. Will that fix any or all of the described symptoms/codes???

I didn't have to drive it much for the past year or so, but now I really need it. Any thoughts are greatly appreciated.

Thanks,

-Keith

Clearing codes sets a P1000 - emissions monitors incomplete..... that's enough for a fail all by itself.

P0442 could be something as simple as a leaking gas cap. You could try a new one (I recommend OEM since I have heard of faulty aftermarket ones). At the same time, check the fuel tank and vent lines for any damage.... this will be a very small leak so you'll need to look very closely. If you don't have a fix this way, some specialized testing will be required.

P0420 could mean a bad catalytic converter... but since you are complaining about rough running, I'd want to be sure that the concern isn't cause by a misfiring cylinder. Likewise, the P0174 - this indicates large amounts of O2 are passing over the O2 sensor. It's very possible that it is time for a set of spark plugs, perhaps there are one or more faulty plug wires or it might even be the classic 4.0 intake manifold leak.

HTH