I have been working on aligning the cam and crank shaft for a week. Still have no clue as what is wrong.

I verified that the white dot on the cam shaft alignes with a mark at rear timing belt cover. Started my belt white line at this position.

Run the belt to Intermediate cam. The belt white line alignes with white dot on Intermediate cam pully. did not find any alignment point on the cover. (The manual says I should find one, but I did not see any)

Look at crank shaft. no white dot on the pully. It has thin metal circular plate, and the edge has a small square notch. Found alignment point at 11 oclock position. Aligned these two points. Verified that everything alignes. Found double white line on the belt, but does not align with anything on the crank gear pully.
Covered up & verified that crank shaft pully is aligned at 0 mark of the cover. pully.

put everything back in place, and run the engine.
Idles OK for about 10 seconds, then the RPM sinks below 500, then recovers up to normal. Ok for few seconds again and repeats the same thing.

What am I doing wrong? Did I damage the engine by mis-aligning the belt last time?

thanks in advance