My cadillac takes off very slow ,then jerks and pick up little speed and slows all the way back down. And sometimes cut off

Dear Debbie,
Fuel filter costs about $ 20 plus installation, catalytic converter about $100 up to $ 600 plus installation..
Go for the fuel filter first.
If it is not that, do a diagnostic check before you do the catalytic converter.
The "cat" seldom is the problem.
God bless your efforts.

Examine your engine mounts and the 'dogbone' at the top right of the engine. The jerking symptoms you describe do sound like a failed mount. The front lower mount is a hydraulic cushion type, and the chief sign of failure is oil leakage from it.

As to the wobbliness and bumpy ride, that sounds like the front suspension struts need replacement. You need good quality spring compressors to try that job yourself.

It is a crude test, but if you can easily bounce the front corners of the car up and down, and it keeps bouncing when you let go, then the struts are worn out.

Look for a blown fuse in the fuse box.

I would check the
Fuel Filter,
Air Filter

Add Sea Foam and this will clean the Injectors and possibly return some of the response.

Did you did any tune up,fuel filter,air filter,coils.

might be clogged catalytic converter it can cause loss of power due to carbon built up that's why it seems like it takes a bit to pick up speed

just had the same issue.. im goignt o tel u what to check because they all might cause the problem.. bad spark plug.. fuel sensor.. fuel injectors.. timing belt.. or the fuel pump.. sound like your car is needing gas flow.. have a mechanic check it out. they shouldnt charge you crazy to check those things

get the shop to check for plugged jets.

Had same problem: cutting out at low rpm, jerking, a huge clunk or shudder at higher speed (like transmission was going out), and rough idle. All these symptoms were intermittent.

CHECK THE FUEL FILTER!! Changed the fuel filter and thing runs fine!!

PS mine 2003 expedition has 105k

Have you tried changing the spark plugs it sounds like one of the cylinders isn't firing