Vibration at a stop.

I just got my Tacoma (2003, 4cyl, auto, 4x4, reg cab) earlier this month, only 75K on it, previously had a tC but I've always loved Tacomas so I decided to finally trade the tC (which after 4 years i regret ever buying it). I'm really happy with the truck EXCEPT everytime I am stopped at a light or stop sign the truck shakes/vibrates pretty bad. It only does this when the truck is in drive and I have my foot on the break at the same time. It smoothes out if I put the truck in neutral or park.
Thought maybe the idle needed to be adjusted so I brought truck back to Toyota dealership, useless, and I quite honestly don't even think they really checked it for me. Said it idles at 750 where it should be.
I learned the truck was sitting there for a little while, so I put new spark plugs in it (bought them at the Toyota dealership only $2 a piece), put in a new air filter, changed the oil with Mobil 1, used a K&N oil filter, and ran some Z-Maxx through the fuel/engine. Did nothing, still vibrates like crazy.
Is this normal for Tacomas like mine? I'm new to this truck, so I don't know if I'm just going crazy or what . I could really use some suggestions. Thanks.

 

My 02 that I had did the same thing! Never could figure it out 100%, but I did end up putting a new rack and pinion steering in it and that seemed to help a lot! Don't know if that's anything to do with yours, but worth checking.

 

I'll have to look into that, looks like I'll be taking it for a second opinion at another Toyota garage. I just don't want to get the run around for a simple diagnosis/fix (if there is one out there). Thank you.
It was still doing it this morning. I'm still somewhat set on it being the idle because when I have my foot on the brake and have the truck in drive at the same time the idle needle moves slightly below 750, but I can't say for sure. I'm no mechanic. Dealerships are dumb, no help.