It hasn't caused me any problems in the months I've owned it and doesn't seem like anything will happen anytime soon. I've driven it for a little over 10,000 miles and its only been to the shop for an oil change and tires. The interior is frequently found somewhat damaged unless its been replaced because it's older.
I bought the vehicle used in 2014 at only 69,000 miles for $2,680.00, I know buying a 15 years old vehicle even with the low mileage was very risky, however what the heck I have good mechanical ability. Gas mileage is a joke for this truck, I think I am going to make a bumper sticker that said "I am supporting OPEC, one full gas tank at the time". It doesn't help my truck had the towing package with 3.73 rear diff gearing, even freeway driving only give me about 15 MPG. Of course in the SoCal freeway we need to drive at 80MPH to keep up with the traffic flow, and this high speed doesn't help.
So the first thing you will have to replace on the 5.7L vortec (L31 Engine), is the intake manifold gasket and replace the coolant with the regular green prestone stuff. This would cost at the minimum about $700 at the dealership. So learn how to do this yourself. Second, make sure you drain and replace filter on the auto transmission fluid, and while you at it might as well install the corvette servo and Transgo shift kit (4L60E-HD2). This make your slush box shift a little quicker and actually make the the heavy vehicle feels lighter on its wheels. Third, check the high pressure power steering hose, most of the time this will also go bad. Fourth, check the brakes and replaced all worn out parts, this vehicle have a very underrated braking system thus you need it at the tip top conditions just to have a decent stopping distance. I also replaced the brake master cylinder to the NBS Tahoe (2001-2003) master cylinder. This help the braking a little but caution still needed when driving this heavy vehicle. Fifth, tune up by replacing the plugs, dist. rotor and cap, and belt. I don't see the need to replace the plug wires on tune up. Use the good oil for older high mileage vehicle, like Valvoline Maxlife. Other things that needed to repair on mine: 1. Passenger door latch - bent, caused difficulty in opening the door. 2. Power window main switch - rear passenger window will not work from the driver controller. 3. Radio light off - didn't fix yet. 4. Vanity mirror light and cover off the sunshade broken - didn't fix yet. 5. Cracked top dashboard - GM used a very low quality plastic in my opinion, all the interior plastics are suspect and especially the top dash cover. 6. Headlights sometimes dimmed - didn't fix yet and not really sure why. 7. Drive shaft u joint broke - this got me and the family stranded in the middle of the freeway and required towing, and the repair and replacement cost for the damage to drive shaft and transmission yoke was a little over $900.00 almost half the value of the truck. I should just left this beast on the 15 Freeway, but i just loved it too much. The way you sit high and have good visibility at all angle it's just priceless! It's also good for towing, even just towing the uhaul trailer. This truck inside creaks and groan as you drive through rough surface and the dash completely rattling during driving through an unimproved road, but still I loved it.
I can honestly say I really enjoy the reliability of my 1999 Chevy Tahoe with it's powerful 5.7 liter engine. I am a HVAC and water-proofing contractor and this truck exceeds all my expectations. I also charter fish on Lake Erie and this vehicle tows my Sea-Ray with little effort. I had to replace the fuel pump a couple years ago..and get a tune-up after 140 K miles, but let me tell Chevy cannot improve much on this vehicle.
I really like that I can slow down..and put her into 4 WL or 4 WH by pushing a button. This baby has pulled much larger vehicles from the ditch with ease. Mine is equipped with rear air/heat and has an after-market 12 CD changer mounted aft with a remote for the front passengers.
I might suggest a better way to have the copper electronic pads on the rear doors supplying power to the lights, etc. Additionally, I feel the blower/heater/AC switch assembly could be improved upon.
I've owned a 94, 98, and 99 Tahoe, all of which have been exceptional vehicles. My 99 currently has 174k, looks great, sounds great, and has been very reliable. It might be slightly more expensive on gas than most vehicles, but the cheap maintenance more than makes up for it. At 140k I replaced the mechanism that opens the driver-side door. It was an easy fix and I was able to do it on my own in about 20 minutes. At 150k I had to replace the fuel pump. From what I understand this is a fairly common fix. Be sure to replace it with a GM factory fuel pump. 174k and only $800 spent on nonroutine maintenance! Looking forward to many years on the road!