Great seeing everyone so eager to help and toss out what we think is the right solution. But before we blanketly send milliemax on a snipe hunting expedition, let's instead prudently ask for more info...
We know he has a '99 but we don't know if he has halogen (most likely) or HID/Xenon lights (don't think they were an option in '99 but could have been or they could have been upgraded). So, OP please clarify and if you do not know, post a picture and we can tell you in a heartbeat (HIDs have a round lens w/in the housing - halogens just a plain reflector).
Anyhow... for the most part, HIDs don't go dim. They usually are either on or off or will flicker...
Halogens on the other hand can go dim... OR... they can go out completely which may just LOOK like a dim headlight b/c of the 'city light' also in the reflector housing. So, let's assume OP has halogens. In which case, an easy test is to pop the headlight pod (as stated, directions in manual and tool in frunk tool kit). Then, since the high, low and fogs all use the same H7 bulb, simply move the one from either the hi or fog to the low and vice versa. W/in the housing, the low and high are stacked on top of each other but low is on top w/ high underneath. Pop the pod back in and test your lights again. If the low now works and the fog or high does not, then it's the bulb. Pick up a pair of new H7s and and change them out on both sides (they typically go w/in a week or so of each other).
If you have HIDs, we'll take a different avenue but dollars to donuts, you have halogens.
Good luck
