Well, you have two options if you want to isolate possible causes:
- To test the bulb/ignitor weight issue you will need to notch a D2S bulb to fit in the D3S receptacle on the projector since it is a lighter design since the magic of the ignitor is made into the ballast itself. D3S uses the ignitor right at the bulb thus adding weight, potentially inducing unwanted vibrations and bulb movement. Even the slightest faint bulb movement with HID will result in very noticeable changes in output or what you're seeing on the road.
- Unfortunately if it's the shield, which I lean more towards, then there is little you could do without reinventing the wheel so to speak. It's more than likely that the solenoid doesn't push the rod that the shield is mounted to with enough resistance to force it to stay perfectly still against the high beam shield until you enable high beam mode (activate the solenoid). Fixing that, if even possible, would be finding a very similar solenoid that has the same exact throw length for the rod but has more resistant in it's rested position (low beam mode). It is a delicate balance however. Also another variable is you have the two posts or 'nipples' if you will on the projector bowl body that the shield moves into in its rested position. If the shield doesn't sit even on both sides exactly or is off on one side more than the other then that in itself is going to cause some of the 'wobble effect' people are seeing. You can see what I'm talking about in this thread http://www.f150forum.com/f83/2013-oe...ld-mod-198278/.
If it really bothers you, and it's not a bulb/ignitor weight issue, then your other option is to swap out the projector for an EvoX. The EvoX uses the same scissor armature type design as many Hella brand projectors. That design has always seemed to hold the shield in the correct spot regardless of road surfaces or vibrations. As I mentioned earlier, the forward folding design leaves some "slop" by design. It's not a Ford F150 thing. It's just the inherent nature of that design style of bi-xenon solenoid.
It has nothing to do with the shroud.
I know that's not the news you want to read but that's pretty much your options. I've done HID for a long time so I guess I've grown accustomed to some of these aspects people determine as 'issues'. It is what it is. People also need to keep in mind that a projector is a magnification device. Any vibration, even the slightest, and you are going to notice it more. Especially when talking about light.