Rep Power: 0

I've been facing this problem since the beginning of December, but I can't seem to pinpoint any causes yet. My engine will start absolutely fine, no problems what-so-ever. When I start to drive it, it will hesitate on me and randomly miss on one of my cylinders. Sometimes it will just skip a beat once (mainly when accelerating, or idling at a stop), but sometimes it evolves into a rough run all around. When it's real bad, it completely misses on a cylinder, and chugs along with very little power. Almost every time, it will get worse after accelerating from a stop while warmed up, or starting the engine while warmed up (like at a gas station). No CEL light at all, and I notice a strong gas/exhaust odor when I am stopped. Also, since the weather has warmed up here in the past couple weeks, it seems to be worse than when it was cold. We just had a cold snap yesterday, and it seemed to run way better than usual.

I can think of a number of things it could be, but haven't narrowed down to anything yet.
-IACV / FITV
-Timing is off (already played with it after I noticed it was off before, but the problem still stuck around)
-Bad fuel injectors(ran some fuel cleaner treatment though the engine a while ago, but nothing changed)
-Vacuum leak
-Bad o2 sensor
-If all else fails, bad ECU.

Where do I even start? I am on a tight budget, so taking it to a shop is an absolute last resort, but this problem is just totally wearing me (and my engine) down.

 
Rep Power: 518

Sounds to me like ignition. Plugs/wires/cap/rotor.

 
Rep Power: 0

I was thinking that too at first, but I changed all of that stuff and the problem still persisted. I almost think that my timing belt wasn't properly tensioned, and it falls in and out of time because of this. Sometimes it will misfire for several minutes and then pop back to running without a problem( or with a few sputters here and there), and this can happen 3 or 4 times per trip. Do you think that's a possibility?

 
Rep Power: 518

Nope. A timing belt will not do this.

That doesn't mean there isn't any problem there, but it cannot do what you envision above.



Loose terminals inside an injector connector? Or any wiring that could affect a single cylinder, IF it is caused by a single cylinder?
Ever left your gas cap off?