98 blazer headlights flicker and brake lights out

At night with the lights fluctuate in synch with what sounds like the fuel pump ( a noise from the rear). The faster I drive the less it is noticable. If I am idle or in park the fluctuation is bad the dome dash and radio lights all flicker. Also my brakes lights just went out altogether all fuses and bulbs are good I already replaced the brake pedal switch and all the other lights work fine (park, turn, reverse). Any one familair at all with these problems. Ps onyone no a good method for changing the spark plugs and wires out?

Try taking a look at your alternator and see what the voltage out put is. With the motor at idle, it should be around 13.5 volts. If not, possible faulty alternator.

The brake lights run thru the $365.71 Multi-function switch (turn signal switch)! Take a look in the back of the Chilton book for brake light wiring diagram.
I recently had to replace the turn signal switch on my '97 due to no brake lights - hazards, turn signals, headlights, wipers, cruise - all worked fine.
Eliminated the Brake Switch and the BTSI (Brake Transmission Shift Interlock) solenoid: could shift from PARK with the brake depressed.
Eliminated the Park-Lock solenoid: could remove key from ignition.
I'm keeping to defective unit to disassemble to determine point/cause of failure.

After a little more thought, I would start by disconnecting the battery, then unbolting the ignition/multi-function wiring harness under the dash, and using some good electrical contact cleaner - clean both sides of the wiring harness. Allow ample time to dry before reassembling and reconnecting the battery.