help needed

I have an 03 3.8 mustang with 123k miles and im having alot of problems right now (or at least i believe all of them are problems)

Ill start with the problem i hate the most and thats a pull to the left under braking... it varies in how bad it pulls depending on the conditions and it seems to pull harder in the cold... i have changed the right front caliper, ball joint, and bearing last yr. its stopped pulling after these changes but it now is doing it again.

The next problem i have is that it seems that the motor runs very flat at times. when i press the gas down the rpms barely pick up and the acceleration is almost non existent. i have just changed the plugs and wires 3 months ago. also during the winter i have problems starting the car... i turn the key and it will start and then immediately choke out and i have to hold the gas down enough to keep it running... while im holding the gas down i smell alot of exhaust and gas. i dont know if they can be related. no error codes at all and its not like this all the time but its been getting worse as time goes.

the final problem i have is that i have a very bad hard shift. its an auto trans and it does it often. this started about a yr after i bought it. im thinking about doing a tranny flush and using some internal cleaner. (dont know if this is a real problem or just how the car is)

i did that back in about February and it didnt change much 02blu

and car stuff i dont have a light on but could it still be a problem without it?

thanks keep em coming cause i want to get this all fixed. if anyone needs more info for ideas i can fill in whatever blanks u have

something to add to the engine issue. tonight the temp was pretty cool id say around 50s and the car ran alot better than it has been.

there is no codes that i know of. and the starting problem is only during winter months when its cold. all summer it runs fine. i have thought about the injectors. what should i use to clean them.. ive been using lucas oil fuel treatments every now and then.

I turned the rotors when i changed the brakes last yr. i didnt see any problem with them. im gonna change the left side ball joint and see if that helps and grease the right side.

and no i havent changed the fuel filter yet.

thanks for the help carstuff... i hope some of this works