Most of the time my truck runs great, but sometimes it idles just a lil rough and has a slight hesitation when taking off. Although it does it more with my wife, it has done it to me also. I was told that the distributor will need replaced by the GMC dealership when we had the spider injector replaced. What do I need to check to see if it's the distributor.... or where else do I go? No there are no lights on the dash board.
Ooh, it's a '93 GMC Jimmy 4x4 4.3L with 165,000 miles and of course auto tranny.

 

It is possible that it could be the distributor, but it's more likely a vac leak, ring wear, or carbon buildup on the valves.

To rule out the distributor thing, take off the cap and check to see if there is any play in it by wiggling the rotor button. If there is any play in it, it's possible that the gears are worn down. I have 165K miles on my 94 and it's still got the factory distributor and gears in it, and there is no play at all. You can also check the timing with a timing light at idle and by revving the engine to make sure that the advance is still working. You'll be able to see it advance the timing when you rev the motor.

You might want to check for vac leaks somewhere. A cheap propane torch kit and a piece of rubber hose work great for this. You might also want to check the compression across the cylinders with a compression tester, and use a "leak down" tester if you can get your hands on one. A full spark tuneup might also be in order. Replacing your plugs, plug wires, distributor cap and rotor button with high quality parts, as well as looking into a new, high output coil. I'm currently looking into a full Accel upgrade.

If you just got the spider replaced, It is VERY doubtful that it's anything fuel delivery related. Do a bit of checking off and you'll isolate the problem. It is possible that it could be the distributor, but there are a LOT of more likely things that it could be.