My initial guess is a fuel delivery problem.
Is the air cleaner clogged? (Based on the description I doubt it is)
Next, remove the fuel filler cap.
Then attempt to start. Is it possible that the vent on the cap is clogged and precluding the fuel from being draw from the tank.
Are all the fuel supply lines tight going into the filter, from the filter to the fuel injection pump tight?
Are the lines coming out of the pump going to the injectors tight?
ANY (even the slightest) leak will cause air to be sucked versus fuel delivered.
Is there a ground connection on the computer? If so check that it is clean and tight.

Eric