I have a 97 tahoe, My question

are you talking about the window? if so listen for noises maybe a popping or grinding if you hear anything there maybe something wrong with the window regulater

The Adjustment for the proper air flow at closed plate,
is set & sealed,do not change it.

I think you got a spring somehow in wrong

Why did you take off the tacm (motor)?

on a lift its about a 4hr job on you back in the ground plan on the day the front diff needs to be removed or at least dropped down but before replacing the pump are you planing on this due to the gauge dropping down to zero?gn had a problem with the sending units that read the pressure thats a 20min job and a $30 part

Might check your antaina plug. may be trying to come unpluged. Good luck to ya.

The brake switch is located on the brake lever assembly just above the pedal...it should slide out of it's holder which is used to adjust the switch..remember that the switch needs to be pressed in for the brake lights to be off..so you will want to put the switch back in and make sure it is pressed against the brake lever

check fuel pump relay, if you it it will click for 2 seconds to start up fuel pump, it not working check or replace your relay, if relay is ok check fuel relay circuit

o2 is a sensor. You could try replacing the correct one (up to 4 o2 sensors are possible any given vehicle). If check engine light is still on, have the codes cleared, have scan performed again to get the fault codes for possibly the specific o2 sensor. Hope this is helpful.

bad earth on the back light ,thats all easy to fix clean contacts

Raise the Tahoe's rear end on jack stands. Block the front wheels and remove both of the rear wheels. Release the parking brake. Remove the brake drum, cutting off the pressed metal washers with a strong cutting tool.
If the drum won't come off because the drum shoes have worn into the drum, retract the shoes by removing the access plug from the backing plate. Push the lever off the adjuster star wheel with a small screwdriver and turn the star wheel with another screwdriver.
Clean off the entire assembly with break cleaner, using a drain pan to catch the residue. Never blow away brake dust with compressed air. Detach the spring from the adjuster level from within the drum by gripping it Detach the spring from the adjuster level from within the drum by gripping it shoe. Remove the trailing shoe and adjuster lever. Remove the adjuster screw assembly. Pull away the retractor spring and remove the leading shoe. Disconnect the trailing shoe from the parking brake lever.

Clean off the backing plate and lightly lubricate its shoe contact areas with high-temperature grease. Clean the adjuster screw assembly and lubricate the threads and socket end. Inspect the condition of the drum itself. If there are any cracks, score marks, deep scratches or discolored areas that can't be removed with an Emory cloth, have the drum resurfaced at an automotive machine shop.

Attach the new trailing shoe to the parking brake lever, position it on the backing plate and install the retractor spring's end into its hole. Re-install the adjuster screw assembly, making sure it engages with the leading shoe. Lubricate and install the adjuster level on the trailing shoe.
Place the trailing shoe on the backing plate, making sure it properly engages with the adjuster screw assembly, and insert the retractor spring into its hole within the trailing shoe. Place the actuator spring within its hole in the leading shoe, stretch the spring and connect it to the adjuster level.
Install the drum back on the Tahoe. Turn the adjuster screw's star wheel until the drum slips over the shoes without rubbing them. Reconnect the wheels once the brakes are changed on both sides and lower the vehicle.

Good luck and go for a test drive. If you could find a empty parking lot, go in reveres and do a full brake application a 7 to 10 times. This will self adjust the brakes to ensure that both side's are adjusted the same. 

looking down onto engine feed belt down to your left around crank pulley, route up putting back side of belt around w/pump then continue rest of belt around outside of remanning acc. leaving top idler last. put 3/8 drive ratchet into tensioner and rotate down slipping belt over idler