Failed emissions test

I have a 95 5.7. It runs perfectly But I had the state emissons test done and it failed. CO% was fine But the HC ppm was 381 at idle (limit is 220) and 386 at 2500 rpm.
Does anyone have a idea where to start? Like I said the truck is running great. I have 30 days to get it straight, Any help would be apprecaited.

Thanks

I also forgot to mention the truck has had recent plugs, cap, rotor, wires, air filter and temp sensor. Truck has always run well just regular maintanace.
EGR valve maybe?

Did you make sure the truck was at operating temperature before the test was performed? If the cat isn't hot enough it will not perform properly.

While I haven't had this problem on my truck, I had a smiliar issue on a car I own with high HC at idle.
337 - first test
Changed PCV, cap, rotor, wires, plugs, oil
328 - second test
O2 sensor changed
280 - third test
Changed catalytic converter
23 - fourth test

Thanks for the responce,
It was at 210 deg for around 1/2 an hour. I am going to do some work to it and make sure I don't have any vacuum leaks or bad wires. The problem is can have it rechecked once for no extra charge. But I may have to start shelling out cash if it fails again.

Any other suggestions are welcome

My HC count was right at the limit on it's last smog test with the previous owner. I installed complete new exhaust c/with edelbrock headers and passed with flying colors. My truck doesn't have a smog pump.

One other thing I read when I was researching possible causes of high HC was that high fuel level in your tank may be a cause as too many fuel vapors are being sent to the TBI and not being burnt. I don't know how true that is though.

Not sure how accessible your cat is but mine had a flange on the downstream side that bolted directly to the exhaust pipe. The gasket was $2.50, when I shined a flashlight into the pipe andlooked inside virtually all the ceramic honeycomb was gone so I was pretty sure that was the problem. Somewhere I read about testing for backpressure in your exhaust system using a vacuum gauge. You could probably google that and it might help you determine if your exhaust is restricted.

The cat "filters" out the HC's, and is most likely your problem. If your truck still has the stock cat, I would replace it.

I guess I'll have to look into getting a cat. It is the stock converter. Thanks for all the info.

Yes, I would check the cat and also the oxygen sensor.

UPDATE:
The truck finaly passed. I decided to check the distributor again and when I removed the cap it was all green . I replaced the cap rotor and coil. Then ran it to the emmissions station = pass :). I don't have the numbers in front of me but they were low. I didn't check the cap at first because it only had about 8000 miles on it and I assumed it was OK. I hope this may help if anybody runs into the same problem.