Hi Ediboy,

I would take a look at when you find yourself out of time. Is there a certain type of rhythm that throws you off? Or maybe a certain drum beat? Then focus on that particular area, practicing it with a drum machine or metronome until you feel comfortable and in time again.

If your musician friends are noticing you are off time, maybe they'll have some advice for you? Sometimes it's easier for others to see where to improve than we can.

Learning more about music theory may help too. If you know in your head how notes are counted out, this may help you execute your playing technique.

I recommend Christopher's lesson on music theory as a good start:
http://www.guitartricks.com/lesson.php?input=10272&c_id=2&ch_id=13&s_id=271