why does my check enigine light flicker when i hot the brakes

What is your question?

as of 2 days ago the check engine light will flicker and if i do not let off the brakes the engine will die it seems like a electrical issue as the speedo drops rapidly and the aftermarket radio cuts out loosing memory of what station it was on as if i had unhooked the battery some times the car will cut out momentarily then go on while going down the road and i may be mistaken but after said episodes the exhaust smells like it is running richer so is it a sensor a bad ground causing back feeding from the brakelights , a faulty ecm any ideas? oh and the car started this monday night 9-17-12 then didnt act up again til this morning thursday 9-20-12