As I mentioned in the title, I have a 1999 GMC Suburban with about 150000 miles. I love the car, but lately it has been acting peculiar immediately after starting it. Whether hot or cold weather, the car will sputter, pop, backfire, buck and generally not get up and go for the first 3-5 minutes the engine is running. I can put the gas to the floor and the car continues to sputter along at about 20 mph - bugging the heck out of drivers behind me. If I do lay on the accelerator however, the car will rev high RPMs as if it wants to go though the gears behave like its in neutral.
After about 3 minutes of sputtering, the car will again start accelerating as if nothing is wrong. This happens every time I start it.
Does anyone have thoughts on what might be going on?