HELP!!! Oil in my spark plugs. Also there is no power when driving.?

[Sdfdsf]

I have a 92 Accord. 3 months ago I had a timing belt replaced and a few days later the valve cover was leaking when I removed it I noticed the seal was too large for cover and it wasn't sealed good.I replaced the valve cover seal. Everything seemed fine with the seal I put on I put silicon on it replaced the spark plug seals and I drove fine for 3 months with no leaks.
3 months later which is today the car lost power and has a bad burning oil smell. 3 of the 4 spark plugs are full of oil 1 is not. When I drive the car it stalls out and loses power until I step hard on the gas and it picks up speed. It will also made a clank noise like something got loose and fell off in the engine but then it drove fine for a while with no noise like that anymore. I took it to the shop and the mechanic said its just the valve cover seal without even looking at it. I want to fix it myself because ti was very easy to do the first time. Is there anything else that can be wrong?if so how do I determine what it is? What do I look for? Thank you