nick-crain-87yota

so i have got a new problem with the old yota,
the problem seems to happen more when it is still warming up but it will continue when it is warm but my idle will suddenly drop to around 500rpm. the thing i find weird is that if i pump the breaks, my idle will jump back up and smooth out. even when its idling "properly" it seems to bounce around going up and coming back down just slightly. i read a similar thread where someone was having the idle jump around and some one said that it might be the break booster but im really worried about the idle drop more than anything. oh and if i have the lights on and i put on my blinker facing up hill my lights dim when the blinker goes so im thinking maybe my alternator but i would really like to get a better idea before i start dumping money into it.
Any info will be very helpful.
thank you for the knowledge in advance.