I noticed you didn't say anything about plugs and wires. A cap and rotor usually doesn't do much good with out them. Change those and I bet your luck changes.
O'Reilly Auto Parts
If this is a Central Port Injection 4.3 (VIN W) you may be experiencing injector poppet failure. A new-improved version of the CPI injector module made by SMP is available through your parts supplier. If yours is a Throttle
Body Injection 4.3 (VIN Z) you may want to check ECT sensor or MAP sensor.
Chino Autotech Inc.