To be honest, I would avoid that generation of Colorado entirely
We have lots of them in our fleet, ALL of the engine combinations except for the V8 . . . and they’re all terrible
Even the 3.7 liter, which is supposedly the improved version, has cylinder head problems, valvetrain to be specific
The build quality is nothing to brag about, either
I’d spend a little more money and get a Nissan or Toyota truck, instead
However, if you’re dead set on getting one of these, here are some thoughts . . .
Make absolutely sure the mechanic performs a compression test on all cylinders. The spec is 215 psi. Don’t let anybody tell you 150 psi is okay. It isn’t. I’ve worked on engines that had 180 psi, and it was low enough to cause severe misfires, and it was due to severely pitted seats. If low, the answer is a new head or having a machine shop do their thing
Have the guy check if the hubs have excessive play. The parts aren’t that expensive, but it’s a bit of work
Have the guy use his borescope to look inside the evaporator housing. Make sure the evaporator isn’t leaking. I’ve done them, and believe me, it’s a LOT of work. No shortcuts here
The front brakes are okay, but the rear drums aren’t the greatest in my opinion. they quickly get out of round, at which point when you apply brakes lightly, they’ll grab hard, and you’ll just about smack your head onto the steering wheel
The cloth seat fabric wears out very quickly
Seat back release handles tend to break
The A-pillar, where the front door check bolts, up is very weak. I’ve seen the sheet metal crack
Problems with front lights out is often due to melted pigtails