2006 Corolla Manual Transmission Clutch Problem?

[paroll]

Hi, I'm not a mechanic so perhaps I can ask you for some help. I have a 2006 Toyota Corolla with manual transmission. Lately (~ 2 months ago) i started to get really weird clutch problem. What happens, when the car is cold, i mean wasn't driven for a few hours, the meshing of the 1st gear at start is smooth and everything is fine, I release the clutch, and everything is smooth and perfect. But then after I drive for a bit (~30 min), especially in traffic, the engagement of the 1st gear becomes jerky especially just as I'm about to release the clutch completely. The whole car vibrates, and I don't know what's happening. This happens when i try to start smoothly, letting go of the clutch slowly, and obviously giving the car enough gas so it's not stalling or anything. No matter what the rpm are 1500-3000 this still happens, at about the time i'm 90% off the clutch. 

Update: To continue, the jerking only occurs at the point i'm almost off the clutch, so ~90% released, and ONLY when i drive for a bit, I assume that the tranny heats up and somethings happens inside. This wasn't the case before and the car has 108,000 miles on it. I don't think the clutch is burnt, I don't smell anything, and the gears shift smoothly all through the 5 gears. I would like to know what could be the issue, before I take it into the repair.

[Arnova]

Something like this happened to mine but it was very jerky whenever on the biting point, starting up or wheel spinning. It turned out to be the engine mounting bolt that come louse and then later fell off.

[roks]

I get this on my car too but only on when cold or damp day and only for first few minutes of driving then fine after that.

I can cotrol the vibration somewhat by giving it extra gas while keeping the clutch down slightly.