sluggish in first & second gear
Does the transmission shift to 3rd gear?
Is the Check Engine Light lit up?
Going to have to know a lot more about the issue. And I’m just assuming this rig is an automatic…
Engine running sluggish or do you mean the engine is revving but the truck does not accelerate very well. There is also the question of how many miles are on this truck.
If you mean it hesitates when shifting into those gears, the engine speeds up but it takes too long before engagement, first step is to make sure the transmission fluid is at the correct level. If it is a proper transmission service might do the trick.
I had a '95 Suburban, I avoided towing because others of that era had a fair amount of transmission failures. I would try a fluid change, but it might not help.
Pretty much the same trans (4l60e in the 1/2 ton, 4l80e in the 3/4 ton) from 1994 through 2008, with some internal improvements. They’re not the stoutest things, but they’re probably similar to the other brands, I guess. Better than Dodge, worse than Ford maybe? Anything from 1995 probably has had to have a rebuild or two by now.
And, since it has been 4 days since the extremely brief first post, I doubt if we are going to get additional details.
Another drive by OP never to be seen again.