Interesting piece. For a piece of music like this, you really need to have a common melodic theme. This kind of drifts.

When I first started, I was doing lots of instrumental tunes. Some were lacking a certain something... a mishmash of styles and instruments that didn't fit well.

Somewhere South of Here: http://soundclick.com/share.cfm?id=8043230

A bit further on, I was learning more about how to put things together so they were a bit more cohesive and enjoyable.

Emerald Eyes: http://soundclick.com/share.cfm?id=9414184

I didn't hear any major gaffs in your tune, just a general "no direction" kind of feel. Yep there's an artifact there at 3:57. When you have those.... regenerate the real track it happens in. Sometimes, it's an issue between 2 tracks. nothing is inherently wrong in either track but put together, it's obvious.
So.... try to get a better direction or theme going and make the instruments the star. Playing a live theme on guitar would certainly help give it some consistency and direction.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.