4X4 control module bad - 400 miles.
Intake manifold leak - 100,000 miles.
Coolant coupler leak - 100,000 miles.
Water leak rear side window - 5,000 miles.
Sun visor vanity mirror hinge broken (driver and passenger sides).
Power door lock actuators bad (driver and passenger sides) - 85,000 miles.
Fuel pump quit working - 70,000 miles.
Overall I really like my '99 2-door 4X4 Tahoe. I special ordered it from Military Auto Sales when I was in the navy. Haven't seen another one exactly like it yet... it is an LS, two-tone paint with sunset gold over charcoal. It's good looking, has lots of power and is pretty comfortable.
At 80,000 miles I had a Rancho 3" suspension lift installed. Rides a lot stiffer than stock but now clears 33" tires. Everything else is stock.
Had some problems that are common with this model, but nothing catastrophic or that left me stranded (Fuel pump almost did... worked just long enough to let me limp home the last 6 miles.)
I've had to replace the battery, alternator and water pump, all between 65K and 75K miles, but those are items that are expected to wear out.
The one major complaint I have is that I have to replace the front brake pads every 12,000 miles or so. That's way too often, even for a lifted 4X4 with 33's. I've had the truck for 9 years and will probably hold onto it for at least another 5 years. Except for the intake manifold leak, I performed all the repair work and also perform all the routine maintenance on this vehicle.