2000 surging!@#$

I am working on my brother's 2000, and thought I had seen it all since I have the same year Montana, but here goes. Thing runs fine, but whenever you have a high load-low rpm situation this thing goes crazy. Just surges like it's missing or something, mainly when going from 3rd to 4th gear and slight incline when the motor is lugging. I checked the plugs, all fine, checked the wires, and have 1000 ohms starting with shortest wire and goes up to 1700 on longest wire, so should all be fine. Is a coil bad? Can a guy test these? I am at my wits end with this POS, and am only fixing it so he can sell it in good running order:banghead:

I am starting to think this platform was one of the biggest failures of GM ever.

check the fuel pressure.

Hold your foot on the brake just enough to turn on the brake lights but not enough that you feel the drag of the brakes. Did it make a difference?

The other thought is to unplug the MAF and take it for a drive.

Turns out I have a head gasket bad now, so the surging thing will have to wait till later:banghead: