About 2 months ago I had my timing chain replaced along with water pump and radiator. I had my brothers friend take care of it. I thought it was running fine until I changed my own distributor cap and rotor then two days later the Rpm when coming to a stop would drop to about five hundred. So I took the car to a shop near my house. The machanic said that my timing belt was off. He showed me that the two timing marks where not aligned with the cylinder head surface. Do those need to be perfectly aligned or can they be slightly off? I was also told that the belt was on to tight. Could me changing the cap and rotor messed up the timing? The person that changed my timing chain to begin with said that it is okay for the timing chain to be off on the timing marks with the cylinder head. Does anyone have any advice?