I have similar problem, not sure if its a problem, but during idle it has a lil stumble. I can here it through the exhaust, it has always done this so thats why im not sure if its a real problem.

 

i have the same problem and changed the tps and coil i did everything and still doing it i cant figure it out

 

check the valve clearances they may be a little tight.

 

I had a similar issue, but with a 3vz (3.0) v6. I would drive down the road and the truck would randomly stumble and buck and then carry on driving like normal. It didn't matter what RPM or gear and it was very random. I checked everything and to no avail.

At last I took the top off the air flow meter; the little black plastic piece that is glued in from the factory. I cleaned the little contact area, it looks like a rainbow shaped black curve that a copper color arm rests on. Once cleaned I NEVER had the hesitation/stumble again.

I posted this in hopes it will help someone who has a similar issue.