In the winter when i would start my car it idled weird.. a couple weeks later it was hard to get my car started... when i start my car i hear like water trickling noises.. i was driving down the road and it acted like it lost it mojo and died.. the machanic did a diagnostic on it and everything checked out fine.

check idle speed control if bad car idling low it will stall when goiing bad it goes up and down in speed idle

With all of the low voltage problems going on here I would check the body computer. That is the only thing I can think of that would cause all of this. Some others may have suggestions on this.

take it to a muffler shop and have the cat converter inspected for failure and blocking the exhaust

Run the fault codes and replace faulty sensors.

Hi
Pop into to your local garage and have a diagnostic test carried out.
Listen to the advise given. It may save you lots of money, especially if you start the "guessing" game.
It does sound like a part may be blocked or failed though, but the sytem needs to be tested thoroughly first.
Good luck
Roger

Possible. It's hard to give you an accurate cause, since I'm not able
to hear the sound. Most of the time, when you hear a slight wrapping
sound, it's a rod bearing,or crank bearing. When the rod bearing goes,
you'll know it,since it will knock like an SOB.

There is a problem with water getting into the wiring somewhere. I notice mine won't start after it rains but as it dries out goes like a dream. I haven't found out where it is getting in yet.

check timing belt

it sounds like when the cat was changed they have trapped a wire or just moved one over a bit and its rubbing think about what items this 30amp fuse is protecting are any of the items close to the exhaust or around that area, i dont see the aftermarket starter doing this after 2 years hope this is helpful regards JR

It sounds like to me your mechanic recommened you change your timing belt and water pump due to a maintance issue. If vehicle still runs good with old timing belt new belt wont change running. Cold weather and low cranking amps (poor battery) will cause starting problems.