I have an 89 ford f150, 6 cyl, 5 speed mazda transmission. I replaced the radio in it a few months ago and ever since then the truck will die completely after being started about 3 times. Every time I start it, I either drive it, or leave it running for about 20 minutes. I replaced the battery when I bought it, replaced the alternator and still no luck. All maintenance has been done i.e. spark plugs, wires, distrbutor cap, rotor. Not to mention I had to replace the injectors due to a leaking one and didn't want to get back in it later so just replaced all of them at once. If anyone know's where I should start looking to fix this short, please let me know.

 

Look at ur voltage regulator

 

On my alternator it has an internal voltage regulator so when I replaced it, the regulator was replaced as well. Do you know where the fusible link between the alternator and the battery is? How do I replace that?