Bill, fuel pressures are the same regardless of the size of TBI. The difference lies in the injectors' flow rating (in addition to the tuning of the ECM for any particular engine C.I.).

Of course, fuel pressure adjustments to the stock regulator are possible within a limited range, to effect tuning needs. Aftermarket mfr's even offer an adjustable fuel pressure regulator, which allows a broader range of pressure adjustments. Check out these links for more info:

http://www.aces.edu/~parmega/efi/tbi_adjust.htm

http://www.cfm-tech.com/gm_tbi_fuel_pressure.htm

http://www.turbocity.com/product_info.php?products_id=437

The Niehoff rebuild kit fits a range of TBI's including 2.8 and 4.3. Check this out:

http://www.partsamerica.com/ProductGuide.aspx?mfrcode=NIE&mfrpartnumber=21732

Before you tear into things you might drive it for a while to see if the problem repeats.

You could pick up one of those "noid light" kits, and if the problem does reappear, plug-in the lights to the injector connector, crank the engine over and see if you're getting firing voltage. That'll tell you right away whether it's an electrical or mechanical problem.

If you're getting voltage to fire the injectors but they're not spraying, then you've got fuel pump/pressure issues or something in the TBI itself.

Fuel pressure test kits are available to check your existing pressure; that may tell you a lot about what's going on. Lots of these at eBay and elsewhere.

Here's a Google search for that:

http://www.google.com/search?as_q=GM+TBI+fuel+pressure+gage&hl=en&num=100

G'luck.........ed