Car has been shuddering while driving and also at standstill while waiting for light change.Feels like the engine could cut out.,Timing belt changed yesterday.Short time later it's back doing same.

it is possible that if the engine just stopped that the timing belt has broken
If the mileage is over 100,000 klms and the belt has never been changed then it is a sure bet
next is the cam/crank position sensors are failing
next is the immobilizer has cut in
lastly the ignition control module has failed
check engine fuses as well

you need a proper tune up, if its a carburator type it also needs cleaning.try to replace all sparkplugs fuel filter.if this wont work your timing is probably off

Your timing belt broke!!!

you can have a look at the state of the belt, make sure its not fraying or missing parts, but you should change it as soon as possible if the belt snaps the cost will be a new engine at worst. min damage a new head. a new timing belt and timed up will cost the lesser of the two. timing belt can cost less than you think.

IF YOU ARE SURE YOUR CAR HAS A TIMING BELT, IT SHOULD BE CHANGED ABOUT EVERY 60,000 OR 70,000 MILES IF YOU WAIT 'TIL IT BREAKS YOU WILL BE SORRY. IT COULD CAUSE MAJOR ENGINE DAMAGE, & MAJOR EXPENSES. GET THE BELT CHANGED

I have the same problem with my 94 LS, its getting fixed now. The camshaft sensor is telling the computer that the timing is off, meaning your timing belt is either jumping or missing teeth, or it may be going bad. It is a very big job, so I suggest replacing the belt, water pump, tensioner, and maybe the seals and pulleys as well. Are you at a lost of power, has you car ever cut off at a stop red light or when driving?

gas? diesel? turbo?what engine? whoever did the timing belt needs to recheck their work they did. and verify timing marks. was the low oil level light on or the low oil pressure light. how did you check the sensor? its either good or its bad. a qualified shop need to ck this for you, this in not a easy car to work on, without proper tooling , knowledge and service manual.

May I suggest to use a OBD2 scanner and see if it could be a setting in the ECU (computer) that could be out... or engine part malfunction... it will scan for any errors... sounds like it could be the airflow sensor perhaps??

drive belts could be loose.

Take the car back to same mechanic immediately