My 2004 Tahoe throws a P0443 code intermittently. I know it has something to do with the EVAP system. Can anybody be a little more specific and may have an idea what I should look for? Thanks

If you want to try throwing the purge valve in it is a good guess. Otherwise you'll need to do some testing with a dvom or similar.
How often does it code. It will not cause engine problems if that is a concern.

It'* totally intermittent. Sometimes I drive for 2 or 3 weeks and everything is fine. When the code comes on. It usually stays for 2 or 3 days and then disappears all by itself. I don't drive the car all that much. I put on 15000 miles in almost 4 years. I looked at my service record and I noticed that the vapor canister purge valve, the vapor canister vent valve and the gas cap were replaced in October of 2019 a little over 15,000 miles ago. I know, it'* EVAP and not a critical problem and I don't loose any sleep over it, but if I can fix it I would like to do that. Btw. which one is the purge valve? Is it the one under the hood or under the car?

Purge is under hood at the intake. That code makes me think it'* something other than the valve. Did they replace those trying to fix this? If so, let it go.

Actually the last fix was for a P0442 and P0455 code

That makes sense. This is more of a wiring/electronic issue.

Thanks 007. I will check and concentrate on the wiring for the purge valve under the hood to start. Maybe it'* corroded or a flaky connection, I hope, but things rarely turn out that easy. I am on Murphy'* ***tlist, you know!

Maybe try to keep in mind if you've driven on excessively rough or smooth roads for the most recent drive cycles before the code sets again. Knowing if shaking is related might narrow down where you search for the issue.

Clear the code and do a bit of wiggling while someone monitors the CEL. We call it wiggle testing and it can help a lot with loose or poor connections.