My step son replaced the valve cover gasket on my 1990 Toyota camry. It will not start now

Wildly varying advice. I would use the lower amounts. They are not under a lot of pressure and you don't want to compress the new gasket too much.

https://www.google.com/search?q=toyota+camry+2.4+valve+cover+bolt+torque+specs

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Easy job to replace. Video in the link.

https://www.google.com/search?q=98+Toyota+Camry+valve+cover+gasket

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JAMES YOU NEED TO CALL TOMORROW TO YOUR TOYOTA DEALER FOR THIS INFO THANKS

Do this when you have a full day and a Red Bull if you subscribe to the stuff.

Torque valve cover 17ft.lbs

If my memory serves me right, your plugs go down through the valve cover. There is a gasket around the spark plug holes that needs to be replaced.That is where your oil is coming from. Replace the outer gasket around the edge of the cover while you are at it. Hope this helps.

The PCV valve? It's on the valve cover. Will see a vacuum line coming off the valve cover.

just try to take the valve cover gasket off first and look and see if there is anything on the underbelly of it were it has been knocking and then go from there.

Replace the half round rubber gromets at the cylinder head ends just under the gasket you replaced

Removal of the plenum is pretty straight forward. You will need to replace the plenum gasket after you remove it; the gasket is not reusable. Personally, if I was going to take the trouble to remove the plenum, I would replace the plugs and wires back there, also.
I know, I have a 93 Camry V6, and it is a real pain to do the plugs and wires with the plenum on. There are no secrets or great tips on the plenum removal, just take your time. Remember that there are different size bolts, and where they go. Please get back to me if you need any more info...Hope this helps, and thanks for choosing FixYa to resolve your issue.
The graciousness of a FixYa rating for my assistance would be greatly appreciated.