Rough idle only when in drive

I’ve seen a couple threads about peoples Truck having a rough idle only when in drive. I haven’t seen a definitive answer on any of them. Any ideas? It’s very smooth when in park but when I’m sitting at a light it idles pretty rough

 

I believe this is the nature of the beast for the 4cyl engines (honestly most if not all in-line 4 cyl engine). The two 4cyl tacos I've had both had the same temperament. I do notice that on initial oil change via synthetic it lightens up for a little while, but soon enough goes right back to its regular cab vibrating in drive.

Its really not much of a issue, just how 4cyl tend to be. If you ever get into a in-line 6cyl engine vehicle its the same thing but even more apparent.

The 3.4 v6 engines by contrast are far more smooth by its nature with the shape of the V they are configured balancing things out.


Edit:
To get more technical its because the joints are rotating in a circular motion pushing the piston rods up and down. That circular motion causes more vibration. In a v6 its doing similar but in both directions sides balancing each other out and using less mechanical movement to do more (as there are only 3 rotating joints to push 6 pistons as uposed to the 4 rotating joints for the 4 cylinders).

Also the reason why in it vibrates in drive is that I would suspect si because that is when the transmission,engine, and all that hubbabaloo is engaged so you then feel the vibration of the moving pistons acting upon the vehicle. Haha thats just me hypothesizing though.

 

@Pervy Ahh I gotcha. I owned a 05 4runner with the 4.0 that was smooth as a sewing machine. Same as my 84 yota. This is the first vehicle I’ve owned with the straight engine. So learning all this as I go. I appreciate the feedback though

 

At a stop, does it wanna go strong and you have to really hold down the brakes?

Maybe try lowering the idle a touch?