87 Camry - 223K miles

Hi Folks ..

I just had new tires installed and after that got the alignment done.
Within a day (i.e. yesterday), I noticed some shaking while driving ..
felt a lot like engine
misfiring.  I had experienced this about 2-3 years back and after I
put in new spark
plugs it started working fine.   However, today the shaking or
misfiring got much worse, gradually
kept increasing.  As I was driving back from work, shaking was
constant.  I see that the
pickup is quite weak now.  I am scared of engine seizing up completely
(really not sure what that means, but
know that will be the end of it)

As soon as I reached home, checked that there were no fluid leaks
anywhere .. nothing burning,
nothing out of ordinary under the hood.  I am baffled ..

- could the alignment have done anything ?  I had a drift to the left
and after alignment still have it.
My mechanic showed me a suspension seal covered with oil .. said I
will need to replace it (about $370)...but also
suggested not to waste money on a car this old.  Before I got new
tires, previous front tires were badly worn out on sides ... as car
was seriously needing alignment.

- could the engine start misfiring all of a sudden ? this badly ?

Thx very much for your assistance