Testors Red giving problems...
Yes some enamel colors are tricky to work with.
Depending on how "thick" you laid the paint, depends on how long it takes to dry and cure.
But... my guess would be either an old bottle of paint, thinned paint, or possibly a bad batch.
After washing my plastics with detergent I wipe them down with rubbing alchohol. I then give the main and larger parts a light wet sanding with 600-800 grit followed by another alchohol wipe down. I don't always primer, usually only on kits that are molded in other than white. I have used two different methods for speeding up the drying time. One was simply a hair drier and the other was something I rigged up. I made a drying rack (similar to those for baking) out of window screening, a picture frame, added some legs to it and stuck a small lamp with a low watt bulb under it.
No matter what color I use (Testors & MM enamels) I always let the parts sit roughly two days before working with them again. That has always been long enough for things to dry without the worry of an ill placed finger print in a glossy car finish.
Oh yeah... I always stir the heck out of my paints with wooden toothpicks.