Troen I'll add a bit on here from my own experiences with it. Spermkiss always has great comments and must say that the power of positive thinking as he suggested is the best way to overcome it.
The first time I ever had anyone cum in my mouth was when I was 13; he was 14. We'd been sex buddies for a good year. We often traded off on sucking each other but would always stop before we came and then would jack each other off to orgasm. However, on this one particular day, he decided to let it go in my mouth...I was repulsed and gagged spitting it all out. I was not pleased and thought it absolutely foul. I told myself I wouldn't do that again at the time.
Speed up to age 19 and I was doing a 69 with a guy about 20 years older than me. I knew there was a chance he would cum in my mouth. When I hit my orgasm, so did he. Again, it was another horrible experience for me as his cum tasted very bitter...I thought I was going to throw up. So I continued to avoid having anyone cum in my mouth.
Speed up many years later; like 14, and I decided once and for all that since I loved sucking cock so much, it was time I learned to accept swallowing. Since many men and women had sucked me to completion and swallowed it all down, it was only fair that I do the same.
So, I remember when that opportunity finally came along, I was ready. It was a major turn on for me because I sensed every little ripple and spasm in the guy's cock...he was thoroughly enjoying himself and I remember taking my time getting more and more turned on sucking him and feeling his cock responding to my sucking...as his orgasm approached, I could tell it was about to happen. I kept milking his balls with my fingers as I sucked and then felt his cock become really hard and his cock swell as his cum poured out of him into my mouth. Since I had been jacking my cock the whole time, the excitement of him cumming and the sensation of feeling his cock loading into my mouth as I swallowed actually triggered my own orgasm. I remember trying to shoot my load in between his feet, but in the excitement of the moment, I couldn't help but get some on one of his feet. He didn't seem to mind.

I think one thing that helps me is that I am so much into the moment and so turned on that taste isn't something that plays with my mind. Naturally after you swallow it down, you'll feel it there and the taste will linger. When I swallow, it's a different kind of hunger...I'm so turned on that the taste only enhances the experience even more...the taste can be secondary; it depends.
There is no doubt cum tastes different with different guys. And as mine4u suggested, pineapple and pineapple juice indeed does make cum taste sweet; it works. Hope it turns out for you....if the desire is really there, you will really enjoy it.

I love sucking cocks and take the guys cum in my mouth but it makes me gag(vomit) when its over. I love doing it but can't wait till the cum is out of my mouth. Any ideas to over cum this?

Sperm is indeed the number one health food, so keep eating it so you can remain vigorous and strong. Plus, it's a lot of fun to get. Using your mouth to bring a guy to climax and feeling his cock throb in your mouth as he gives you his load is the greatest thing in the world.