This is where a basic repair class should come in handy. The knock sensor is looking at the exhaust to see if the mixture is correct (at least on my car). The computer uses this to adjust the fuel mixture and in some cars retard or advance the ignition. If your timing belt was getting to the end of its life it will have both stretched and may have worn.
The belt has cogs that interact with the cam or cams and the crank.
In some cars it also drives the water pump.
This site has a number of good pictures
Auto Timing Belt Repair | Last Chance Auto Repairs
Once the belt has worn it can throw off the timing enough to foul plugs and sensors. If it had been a while since you changed the plugs and wires then this can happen even faster.
As to why it ran good on and off it can be as simple as the weather, the temp, and the operating temp of the car.
My car currently needs a cam sensor installed its a $20 part and a 8 hour job.
Because the computer is not entirely certain of the cam position is stumbles a tiny bit until it is warm.
Your chosen position is a good one and if it is something you want to do just keep plugging away at it.
Auto mechanics can make good money but in most markets the properly trained ones have to compete with a vast number that are often in over their heads. These shade tree mechanics are often good at many things but when a proper diagnosis is needed turn into part swappers.