Tell us more about the full length recoil spring guide rod from wilson combat
I would put the stock Colt guide rod back in, for starters.
So all the stoppages present themselves as failure to feed, but not with a fired case still in the chamber, right?
(What brand, bullet profile, and weight is the ammo?)
If yes, remove the extractor (clean the tunnel where it lives with a worn .223 brush, while you're at it).
Does the pistol still have failures to feed with 1 round in the mag?
It it will feed OK with no extractor, you likely have an extractor tension or clearance issue.
If it won't feed with the extractor removed, using quality ball ammo, the possibilities are:
1/bad magazines (use Wilson, nothing else)
2/burr at the firing pin hole in the breechface. Gently chamber it with a drill bit, by hand.
3/breechface dimentions out of spec
4/burr in chamber
5/some other issue - gunsmith should be able to figure it out.
This should be a pretty simply fix if you have someone who knows what they are doing look at it. Don't let it sour you on Colts, as they are excellent guns.
Know however, that the shorter guns are less reliable than the full size ones. This is due in part to the altered timing of the cycle of operation (sped up), the heavier recoil springs, and the lessened stroke of the slide.
The shortest semi-auto handgun I carry is 4".