I have a 98 cadillac catera im have problems starting it it will start sometimes but when it start and i push the gas it ride good but when i turn it off it goes back to the same thing not trying to start

ARE YOU GETTING ANY MESSAGES? STARTER DISABLED MESSAGE? DO YOU HAVE PASSKEY? VEHICLE ANTI THEFT SYSTEM VATS FOR SHORT? CHECK YOUR IGNITION SWITCH I REPLACE AFTER MONTHS OF MESSING WITH THIS CAR 96 STS GOOGLE YOUR CAR AND PROBLEM A WHOLE LIST POPS UP WITH GM CARS WITH STARTING PROBLEMS HOPE MY NEW IGN WAS PROBLEM DONT KNOW AT THIS TIME.

Check the catalytic coverters to see if there plugged or start the car and listen for a rattling noise