I have a 2001 Buick Lesabre, just had new tires,breaks, and an alignment in which they said the alignment I did not need because it had not changed since the last one, but my car shakes when starting till I get to around 45 to 50mph and I cannot figure out why. Any suggestions?

. Check engine mounts.

. Check half axles.

. Check all suspension parts--struts, lower ball joints, outer tie rod ends, sway bar end links, and wheel bearings. Besides checking for wear, ensure parts are torqued to spec.