If you suspect temperature is an issue (you live in the NE, right?), try this trick...
Get a large bowl or bucket and fill it with some warm/hot water. Take your paint can, shake it, then place it in the container of water for about 5-10 minutes. Then take it out and shake it AGAIN, then spray.
Soaking in the warm/hot water will cause the paint in the can to mix more thoroughly, AND it will cause the droplets in the spray to be about 50% smaller when sprayed, thus giving you a better-looking paint job.
Well then, I DON'T recomend using stripper on them. If they were fiberglass, I'd say to strip them, and try a different paint, but stripper will eat plastic. You may have to sand them smooth, primer them, and repaint or rub-n-buff.
If you have to sand them down, use like 400 or 600 grit wet/dry sandpaper and wet it with mineral spirits. Cuts the work down considerably.
I agree with warming the paint up. Silver, Chrome silver ecspecialy, can be a Booger some times. The piece your painting needs to be room temp also. Spraying warm paint on a cold piece of plastic can affect the outcome also. Chrome paint looks alot better when you apply "Wet" coats, but you've got to watch out for runs.
You might want to practice on some other scrap first.
If you get it right it can look Really nice.
You can see my RKT ROTJ gauntlets : http://photos.yahoo.com/roberteidemiller in the Emergency sale folder. it is Krylon Chrome silver. also used it on the nose piece of my Tusken.
But back to the question, I agree with warming the paint .