The funny business with the PSI is what Ira said - a bad check valve in the fuel pump. But it creates a very subtle delay in starting when failed - only a second or so, not the 3 or 4 attempts at starting mentioned here. Frankly - I wouldn't bother trying to fix the check valve - its not your problem. Eventually the pump will go out and you'll get a new check valve with the new pump.

Something else is probably causing the hard start. Is this cold, warm, or both? Does a quick press of the accellerator pedal (triggering extra injector squirts) help it come to life? How did you check the sensors?

Also, before looking at the FI system, I've usually found it beneficial to make sure the other components are in proper tune as they can mask or create problems with the FI. Adjust the valves, check and clean the plugs, set the timing before tinkering with the FI. When you check the sensor readings with a multimeter my technique is to pull the plug off the computer and check the readings there. If you get a bad reading check at the component too - this will tell you if the fault lies in the wiring or the component.

I also wouldn't worry about the 30psi vs. 28 psi. You can use the fuel pressure adjsutment to fine tune the mixture. The little knob on the computer box itself just fine tunes a special idle setting - and has no effect on the off-idle mixture. A little time spent driving it hard, pulling/checking the plugs and tweaking the fuel pressure will get you to the proper mixture setting. Although - this is rarely very far from 28 psi unless the engine has been modified (displacement, cams, better breathing) and its fuel requirements have changed.