Changed plugs new fuses new ecu and relay replaced fuel pump just about to give up lol

I have a short in my 30 amp D.C.C "ECU-B”, "RAD NO.1” and "DOME” fuses which is causing all sorts of problems which include hard shifting, throwing OBD codes P0420 and P0793, to having an annoying squealing engine noise that is coming from the car speakers. I did recently install a new aftermarket stereo in the car which was working fine until my husband decided to go messing around with things and even somehow hooked the stereo up direct which I believe could be the reason for the headache I've experienced over it. Now I am no mechanic and have never even worked on a car before so I am learni… Read complete

It suddenly occurs to me that my car's speedometer and mileage calculator stop working. I've already replaced the speed sensor on top of the transmission as the computer announced failure p0500 in the speed sensor, but there has been no change. The vehicle starts and stalls, and even more, when it is parked in the sun for a while, it won't start again. Only after it has been cooled down by the air conditioning you can start driving it. Please someone help me.

Engine seems to run fine but you can hear a slight up and down rpm, very faint sound. When you excelerate it feels like your riding over a small wave. I changed all spark plugs to iridium, new fuel injectors, new ignition coils and replaced plug on cylinder 3 ignition coil. Engine light will not go away and get p0303. Seems like coil is not communicating with ECU. I get p0172 as well but replaced MAP and up/down o2 sensors..HELP! Btw my cylinder 3 coil burn out twice in the past, it must be an electrical problem

Mi camry 2006, tiene el código p0500, le eh cambiado el sensor de velocidad, la computadora y el tablero y aun marca el código el velocímetro aveces trabaja y después de desploma ya no trabaja y depronto trabaja ya no se que más hacerle los sensores del abs también los cambie

Code reads p0500 and just changed the altinator and battery but altinator still don't have power

No spar to plugs,tryed new distrupitor,ignition switch and engine computer.