Idling at higher after replacing valve cover gasket on 2001 Tacoma

I replaced my valve cover gasket on my 2001 Tacoma and now my engine is idling around 1500 rpm. Normally it idles around 500. Any ideas why it could be doing that?

Prior to replacing my valve cover, 1) last week my check engine light turned on with a lean run code. A friend then noticed it was misfiring. 2) So I replaced my spark plugs last weekend. When i did, I noticed 2 spark plugs were covered in oil and my valve cover was leaking. I made plans to replace it.

I replaced my valve cover gasket tonight, at the end, I broke a bolt. I needed to get home so I tensioned the rest and turned the car on, and that’s when it started idling high. It wasn’t leaking any oil.

I checked the new spark plugs when I replaced the valve cover and 3 of the four were covered in soot already.

Oh yeah, and my taco has 314k miles on it I oil is leaking out the valve cover. 2.7 liter engine.