PLEASE HELP ME!!! DOES ANY ONE KNOW WHAT'S WRONG WITH MY CAR??

I'll throw my 2 cents in here...

It sounds to me like a fuel problem.
Filter or FPCU.

The bit about it fluctuating between 2 and 3k at idle sounds to me like fuel supply, a failing PTU would not do that.

 

I had a similar problem in the 280. Started fine, you drove off, it lost power and stopped. Would start OK, drive off, lose power and stop.

Filter inside the fulel tank on the 280 is like an overgrown coke bottle with the takeup in the bottom. There is also a pipe to the top, so what happened was that the fuel level inside the filter dropped until it drew air in from the top and the engine stopped as it does not run on air.

The Z32 pump has a sock around the horisontal intake pipe at the bottom of the tank, so it would not draw any air. If the sock gets clogged, it would cause fuel starvation though, so you would lose power and if severe enough it may stop.

It may not be obvious even if you take the pump out and have a look.
Easy enough to clean it though with some compressed air and a bit of massage.