I am wondering if you created a leak in the intake manifold or the carb. gasket when you tried to start it with the carb. cap on.
An easy way to check this is an old backyard method take a can of shaving cream,start the car and put a small amount around the carb.gasket and intake manifold gasket pay close attention if you see the shaving cream dissapear somewhere, you have a leak.
P.S. don't feel bad I did the same thing several years ago good luck.