Some body please help ...

89 Legend having drivability problem with following symtoms:
- When driving, the car hickup, chocking, and hesitate to run.
- White smoke with burning smell come out from exhaust pipe.
- Idle irregular, rough, and low but engine does not die.
- No [Check engine] light on.
- Engine is very to start but the car is not drivable.
- Timing checked OK (15 Deg before)
- Don't think is transmission problem.

I have done the following :
- Replaced timing belt, timing checked OK (15 Deg before).
- Idle adjusted (no blinking light at ECM).
- New spark plugs with correct gap, wire set resistance checked (less than 8Kohm)
- Distributor cap and rotor in new condition.
- New fuel filter, and air filter cleaned.
- Replaced MAP sensor, crank position sensor, fuel pump main relay, and fuel
regulator with used parts, but thare was no change in symtoms.
- Vaccum is 19 Hg with steady needle.
- EGR system functional tested OK (engine died when apply 5 Hg Vac to EGR)
- Air bypass control valve functional tested OK.

What is the chance that this caused by the fuel pump ?
Would some one please help... Thank you.