Tune Up?

i have a 97 blazer with 148k miles. how often is a 'tune-up' required if at all ? just curious. also, when i got my tires rotated last week,the machanic told me the brake pads and shoes were gettin wore out. well duh man, its not brand new so of course its worn. but anyway, how often do brake pads need to be replaced also? that were prolly done about 20-25k miles ago, so im jus checkin the life on them. if they can wait until spring itd be nice because its too cold to be doing them, and i can change them myself if i get the parts. theres no noticeable squeeking or rough shakes when i brake and they seem to work alright... thanks

A complete tune-up should be done every 3 years or 50,000 miles, this includes plugs, wires, cap, rotor.

Fuel filter and pcv valve every two years.

Air filter, depending on conditions, should be changed every 6 months.

Cooling system should be flushed and new rad cap installed every three years.

Full lube every oil change, this includes:
greasing the front end (upper and lower ball joints, inner and outer tie rod ends, idler arm, and pitman arm...11 fittings total )
oiling the door and hood hinges
graphite in the key cylinders

Check the brakes, hoses, belt, and wiper blades regularly and replace when needed.

More detail about brakes:
Depending on your driving style and the quality of the brakes they will 6 months - 6 years.... you can't put a set time or mileage on brakes they need to be checked and replaced when needed. To check:
look and make sure you have at least 1/8 inch of pad left. (brakes have "squealers" that will let you know when excessively worn)
check the rotor for signs of damage...grooves, scratches and burnt marks.

Forgot to mention,

Every two years:

Change the tranny fluid and filter

Drain and refill the transfer case

Drain and refill the front and rear differentials.