[Dream240]

Your problem is under your valve cover.

Think about it. You do an oil change and replace the valve cover gasket, which means you had to remove/replace the valve cover. You either dropped something inside the head that you didn't notice or you loosened a bolt that you didn't re-tighten.

Now unless you fucked with something else that your not telling us about, that's where your problem is.

And the valve cover is not that hard to remove. Shouldn't take you more than 15 minutes...with a 5 minute coffee break.

Take it apart and stop asking questions. This is really simple mechanic logic...If you didn't have the problem BEFORE you messed with it and now you have a problem, then the problem is related to what you touched.

Now go fix it.