why is my suburban "surging" at cruising speeds?

The first thing I recommend checking is the fuel pump pressure. Please understand I have to say this... It is federal law that the catalytic converter is in place. With that said, you have to keep in mind that the removal of the cat can cause issues with driveability. The O2 sensor sends information the the computer identifying exhaust emissions. If they are out of control (no converter) the computer tries to compensate for the difference by adjusting fuel mixturers. Chances are that is at least part of the problem. Start with fuel pressure and also check the fuel pump regulator to make sure everything in within spec. It sounds like you have worked around cars, but if you need directions, go to our homepage. Under the DIY section there are directions and a video explaining how to do it.

Let me know what you find and if you have further questions.

ya, i understand the disclaimer. seems odd that fuel pump pressure might be an issue if it pulls hard under heavy acceleration. i suspected that perhaps the removal of the cat could cause my issues. i wonder if i add a more "free flowing" cat, i would solve my problem??

i'll have to check it out but does the "diy section" describe how to monitor fuel pressure while driving

Actually, the pump may not be the issue. It could be the regulator. And yes, a free flow cat might be helpful. As far as the DIY, it explaines what should happen when the throttle is hit. Basically, you will see a sudden drop in pressure that regulates back out. If you check it when driving, it should still maintain the manufacturer's spec. I'm seeing between 9 and 13 psi on the TBI models.