Car shakes while in reverse

Then stops when I put it in drive and at 45-75 mph it starts shaking again and acts as though it is running out of gas. This is has been happening for about three weeks or so now, it comes and goes, it will get really bad where it is almost shaking all the time and then it will completely stop shaking, then gradually start again, also when I park the car and get out it has a strong odor of burnt gas or oil it almost smells like rubber and gas combined, it used to shake in reverse and in drive at any speed, then stopped shaking at low speeds in drive and only shakes at higher speeds, I have changed the spark plugs just two weeks ago, and it has had an oil change in Dec, its only Jan.

I have run out of options and can't afford to take it to a mechanic, can anyone give me a hunch in the right direction, i've heard that it could need its fuel cleaned out because my fuel cover broke in NOV last year and I didn't get it fixed till mid DEC, so my grandfather said that maybe it has some dirt and water in the gas, ive also heard that it could be my fuel filter that is dirty, I just dont have the time or money to replace everything everyone has told me about, I took it to a autozone and had a diagnositcs run on it and it said that my cylinder 4 was misfiring, that I had an oxygen sensor detection, and something else about a cam drive