Pulls too much to one side and unstable especially @higher speeds

It would be an alignment issue with the toe angle

 

Go to another align. shop an get a print/out of current settings?

 

Get a print out of the alignment, especially the camber. If I recall correctly, most of those freightliners cannot have the camber adjusted without heating and beating the front frame thingy that runs between the wheels.

 

Pulling to one side can be caused by radial tire pull. Rotate steer tires and if the pull changes sides it is the tires. I thought that was old school car tire problems but Snowey reeducated me . I tried it he was correct. The wobble left and right sounds like tires out of round on a outside rib which may be caused by incorrect tire to rim mount. Is your alignment shop and tire dealer the same company? If so the reason for baha's suggestion is doubled. Out of round tires can be checked with Wiley Wonka's expensive bad egg machine, a 4 x 4 block close to the tire. Rotate the tire while looking at run out in the center and with the block turned at a slight angle to each outside rib. Safeyankee there is a lot of info on this sight under the search feature, educate yourself. Find a good shop.

 

Most of the time, I have found a right pull is caused by the drives. Most alignment shops go for "in spec" and wont go any further. Since the rear axles have +/- in either direction, but most of the roads are sloped slightly to the right, any right steer in the drives is made worse, even if they are "in spec". Measure center to center of the drive axles left and right. If the left is even a little bit bigger, it's steering right. Even dead on will cause most trucks to very slightly drift right.

We've played a lot with alignments to get our tires wearing good and this is what we ended up with:
On the steer, camber/caster in spec, but equal left to right. Toe is set to 1/32" toe-in (then tweaked if the tires show any signs of feathering). Usually 1/32" toe in is good for us, but sometimes you just have to give the truck what it wants.

We shim the front drive to be parallel with the steer, dead on, spent the time to get it right. The rear drive is then set up so the right side is 1/32" wider than the left. The 1/32" difference offsets the slight right pull from the grade of the roads by giving it just a tad of rear steer to the left.

Feel the steer tire feather. If you run your hand across the tire and it's smoother one way, the tire is not going straight down the road. If it's smoother pushing toward the truck, it's towed in. If both tires show signs of toe-in or toe-out, you have a toe problem. If one shows signs of toe-in, but the other toe out, the truck is getting pushed sideways down the road and most likely that problem is in the drives.

All this is of course, is after a complete steering/suspension inspection and any worn parts replaced. Most alignment shops only care about a screen turning green to get paid, it pays to find a shop that specializes in alignments and cares about your tire wear. Some of the worst alignments I have ever seen were on brand new trucks rolling out of a dealer. The first thing we do to a new truck is an alignment.

 

I had a perfect alignment on my old truck and pull to the left, it turned out to be bent tire. Bridgestone with good tread, but the casing was kaput .....