Why is my Engine shaking in idle?

Flashing check engine light? That's universal for a misfire.

Have your local autoparts store pull the codes and determine which is misfiring. THEN, walk out of the store, WITHOUT buying one of their store brand coil packs. Misfire on a 2016 like yours is most likely a coil pack gone back.

You can confirm by identifying the cylinder that's throwing the misfire code (lets say Cylinder 3 as an example), then swapping that coil pack to a different cylinder location (lets say cylinder 1). Clear the codes, drive around till it throws the code/check engine light again, rescan the computer and see if the new code says cylinder 3 or cylinder one. That'll tell you if it's wiring, spark plug, coil pack or something potentially more. If you confirmed it moved cylinders with the coil pack swap, go source an OEM one (Dealership, junkyard, AMAZON, etc).

If you're due for spark plugs, it'd be a good time to change those. Denso or NGK are the only brands I'd recommend (and are OEM for the truck).

 

I have 03 Tacoma 2.7l, witch is the one having the problem

 

Same applies if that 2.7 has coil packs. If it has cap/rotor and spark plug wires, then you probably just need to give it a good tune up with new: Cap ($20), rotor ($10), plugs ($25) and wires (maybe $100?). All very DIY friendly.

 

Have coil packs, if I have them plugged in the wrong order ,will that do it, just replaced the head gadket, maybe plugged them in the wrong order

 

How do your motor mounts look?

 

My truck was shaking at idle.... buddy told me to clean the throttle body... runs great now!!!

 

That'll change the firing order and is very bad. Coil packs, like a single coil pack with separate spark plug wires going to each spark plug OR a engine wiring harness going to coil packs that mount directly onto the spark plug?

Typically, the first can be wired wrong, and needs to be checked/corrected ASAP before you do potential damage with a wrong firing order. The second cannot easily be wired wrong. Usually the engine wiring harness has only enough slack that wiring the leads to the wrong coil would be impossible, if not glaringly obvious, unless you've altered the engine wiring harness.

 

If it's like mine, you can't. My harness barely has enough wire to unplug it from the coil.

 

Cleaned my throttle body and MAF sensor over the weekend. Very carefully. Now noticing a slight shake at idle.