Tune up now shaking problem

have scanned for any codes---can need tune up--cat conv failing--sludge--pulley failing--drive trane damage /worn parts

Is it possible you might have installed the thermostat upside down? How long was it hot? You might have burned your engine up. Check compression, each cylinder should be over 100 at least, and around 130 at best.

CHECK FOR A BROKEN BELT IN THE TIRE

what about dirty injectors
no mention of using injector cleaner or having the injectors cleaned

take car to local part store they diagnose for free ....it might just need a tune the diagnose can tell you exactly what is causing the check engine light to come on

MOTOR MOUNTS, TUNE-UP, FRONT SUSPENSION, TRANS MOUNT, TIRE PRESSURE OR BALANCE WHEELS

Suggestion only! If you had no shake before the tranny work,then retracing the steps backwards is a good way to find the new problem.
Go back to the tranny shop and complain #2 go to another tranny shop and get a professional to look at their work.

Drive shaft universal joint worn.Or bearing worn.Have them checked out Before driving any distance.Hope that was help full

try a tune up

i have a 1995 buick century 6 cyl, some days it does not engadge in each of the positions to get to drive you don't hear thre shifting so I return it to park wait till the engine is warm and then it engadges. and between 50 and 60 it shakes but goes away after or under 50? I have 118k miles on it. What is wrong?