Hyundai Repair: 2001 Hyundai Accent- fixed 2x for slow shifting, running rough- now loud noise., clogged catalytic converter, hyundai accent

Question
hello, my accent was fixed twice now at the dealership.  The initial symptoms
were that at certain speeds, like 30, 40, btwn 60- 70 (when the car shifts
automatically)  there would be hesitation and vibrating- especially toward the
higher speeds.  Both times they copuldn't figure out why it was running
rough.  They said carbon was building up on the fuel injectors, but they didn't
know why.  After they were cleaned, (both times) the car ran fine for a couple
of months.  Now it's the same old situation, but worse.  It is getting to that
point where i am going to take it in again, but today when i was driving on a
back road- i ran over a small puddle.  After that, the engine suddenly got
extremely loud - it seems to be whirring a little too.  No lights came on at all,
the car temp and fluids are all normal.    What could possibly be wrong?

Answer
The possibilities for problems are large.  If cleaning the injectors cures the issue, I might expect a problem with clogging of the injectors or perhaps a fuel pressure issue.  Even so, these are rather low percentage guesses.  If you had one of these issues, I'd expect your check engine lamp would also be on, but that's not the case.  

The best way to approach a problem like what you describe is to actually feel it happen.  A technician that's good at driveability diagnosis will know what an ignition misfire, low fuel pressure, or clogged catalytic converter would feel like and will be able to narrow his search for the problem based on what he feels.

The only type of noise I can think of that would be caused by running through water would be a squeal or chirp from the drive belts.  If the engine is making the same noise as before, just louder, you probably need to check things like the exhaust.