Like others have said, the single stage paint isn't doing you any favors. I've heard people say single stage is easier than spraying base/clear, that is incorrect. Much less room for error, a beginner painter would be much better off with base/clear sprayed separately as opposed to single stage. Base coat is easy to spray and you can use multiple coats for proper coverage and wet sand if needed in between and after completion. Spraying clear can be tricky however, it's a bit of an art form. You spray it on wet, as thick as possible before it runs, that's your biggest enemy, if you spray it too light, just re-do it. Blending clear is also a bit of a bitch, so you need speed on large panels, a small compressor won't cut it.
At the end of the day, it's an engine bay, and I'd say it looks pretty damn good all things considered
