Ok so my t4r is having a few problems after 230k miles, such as,

Rough idle at stoplights
Shut offs at stop lights after highway driving
High rpm shutters 4-5krpm's
Strange smell from exhaust if i dont run high test gas
Long starts on first startup, atleast 5 or 6 revolutions of the motor before it fires

Ive already changed the fuel filter, spark plugs, wires, air filter and thats all i can think of to do.

Im wondering if my cat is stopped up and causing this, or do i need new coil packs, i have no check engine light on, so im stumped.

And if i were to bust out the cat temporarily until i can afford a new high flow cat would i be at risk of setting off the check engine light and if so what could i do to keep it from coming on?