Hi AZ,
On my B5 A4 2.8 V6, it had burning oil smell under the hood.
After checking, I found that the valve cover gaskets were leaking oil.
I replaced the gaskets and oil stopped leaking.

Now, I have some sort of plastic burning smell after driving 5+ miles and I have no idea where this is coming from.
I took the plastic engine covers off to observe where it's possibly coming from but unfortunately there was no clear sign where it's from or what's causing the smell.

I wanted to see if anyone had similar issue on their B5 A4 2.8 before and what the fix was.
Also, is there some hose that gets clogged up commonly that I should check for potential problem?
Since I only get around 200 miles from full tank (50% city/ 50% hwy driving), I cleaned MAF sensor but it wasn't that dirty and it didn't make any difference.
I love the car and engine is very smooth and strong. The only complaint is the plastic burning smell.
BTW, the RPM idle is not solid stable either. It is at 750 RPM but moves up and down by very little amount, which I cannot feel but if that's some sign?

It's sunny day on Sunday and time to work on the car. I would appreciate for any help that would save my time.
Thank you