Did you do all the routine stuff like adding dry gas, remove the gas
cap, changing the fuel filter, air cleaner, plugs and wires and rotor
and distributor cap?  Usually only one injector will go bad and the car
should at least act like it is running on two cylinders.  Also drain out
some gas and see if it looks OK.  I have gotten bad gas several times.

Start with the basics.  Clean the grounds on the intake manifold, the
battery negative to block at the block, and the static strap between the
engine and the firewall.  Make sure all the hoses and tubes have no cracks
or breaks and are held or holding themselves in place with no cracks at the
ends.

Remove and clean the following connectors.  AMM, throttle switch, and temp
sender for the ECU under the third intake runner.

Then clear the ECU of codes.  When symptoms reappear, retrive the codes and
start from there.  Sometimes the code tells you right out what is wrong.
Sometimes it takes a bit of sluething to figure out what is causing the
problem.

Don't know how to clear or obtain the codes.  Get a Bentley Manual and
follow the instructions.  That manual will also guide you through testing
individual components based upon the code retrived.

Duane