My radio went out in my 2004 isuzu ascender

SOURCE: Isuzu Ascender Fuel Filter

The fuel filter is located with the fuel pump inside the gas tank

SOURCE: I need to replace the water pump on my 2004 isuzu

Hi,
Tipping my hat to you... I would recommend going to an auto parts store like Autozone or O'Reilly and purchasing a Chilton repair manual, specific to your model. I always think it's a good idea to own a light repair manual if you're going to keep the car a while.
Good luck with the project! You can do it!!

SOURCE: my gas mileage is horrible. what can i do to fix

Okay... K&N drop-in filter, NGK V-Power plugs (and NGK wires), run tires 2-4psi over manufacturer's recommendation, replace fuel filter anually, use a good fuel system cleaner every oil change, use synthetic oil in the crankcase, transmission AND differentials, drive with windows up and A/C off (just vents), drive 55mph on freeway (this one is HUGE), slow acceleration and try not to drive short distances. These are all "hyper-mileage" techniques that garner better fuel economy. If there is a mechanical problem causing the fuel economy to be bad, the spark plugs, wires and filters ought to be a help.

i hope this helps out,
matthew

SOURCE: 2007 isuzu Ascender keyless entry. I can hear a

sounds like a bad lock mech open door up and check acuator

SOURCE: Is there a repair manual for a 2004 Isuzu

No, there is not one available. However, the Chevy Trailblazer is basically the same vehicle and there is a repair manual available for that.