Your symptoms could mean many things… I would replace the Fuel Pressure Regulator if you are unsure how long ago it was done. Other causes could be bad Oxygen Sensor, bad thermostat, or possible vacuum leak.

Have you pulled the codes to see if the car knows what the problem is? It is very easy to do and instructions can be found here: http://www.sjmautotechnik.com/ecufv8.html

If you have any questions, let me know.

Good luck,

- Jeremy

1990 V8Q Zyclam Portland, Oregon (USA) http://www.MyV8Q.com/ Fun, Fun, Fun auf der Autobahn