I have a stock HU from a 2004 Silverado i just need to get a connector. Do you think it could be my head unit thats in there now?

I havent done anything to the ignition system or the spark plugs. Last thing mechinical that was done to my truck was a rebuild transmission and the routine oil changes but since then i've ran a system without a problem but when my door speakers when out i got new ones and since putting the new ones in i've had this problem.