I have a 1997 gmc jimmy and it is hard to start when it is cold i think its a choke problem.

Hello,
The choke on your vehicle is a computer controled fuel system. It is usually a fuel pump but sometimes a Distributor cap and rotor problem. I would first check the distributor cap and rotor. Look for white corrosion in the cap and in the bottom of the distributor. If you see the corrosion in the bottom of the distributor clean it out with brake cleaner.The Coil wire some times fails causing a hard start situation. I suggest checking these things before doing any thing with the fuel pump. I would also replace the fuel filter and spark plugs if you do end up replacing the cap and rotor.

I hope this helps.

Roy