Well, i tried searching on google and formula1.com for the rule or regulation that states when a car can be DQ because of his slow pace, putting in danger other drivers, but i cant find it.
Is there a rule approved by the FIA to do that?, because i remember Paul Dana being DQ in Indycar racing because of his slow pace.
Any help is welcome, thanks

FIA site would be the best place to look

http://www.fia.com/sport/Regulations/f1regs.html

You might find something about black flag rules in the standard regulations which will cover what you're after rather than the F1 specific stuff.

EDIT: Appendix H has the bit about the flag rules

e) Black flag with an orange disc 40cm in diameter:
This flag should be used to inform the driver concerned that his
car has mechanical problems likely to endanger himself or others
and means that the he must stop at his pit on the next lap. When
the mechanical problems have been rectified to the satisfaction
of the chief scrutineer the car may rejoin the race.

I read and downloaded F1 and FIA rules, Codes and that stuff, and in Drivers appendix "driver should drive carefully" in penalties there's nothing related. But i swore there was a rule that stated that if a driver was 107%off pace he shouldnt race.

107% was the old qualifying rule. Any cars that couldn't do 107% of the pole position time weren't permitted to start the race.

I thought they dumped it a few years ago, but it could be in there.

Quote from DarrenMarsh :

I thought they dumped it a few years ago, but it could be in there.

It was dumped when they changed from the 1 hour/12 laps format.

F1rejects.com has this story...IDK if it's any good

http://www.f1rejects.com/interviews/pease/index.html