Hi, i have a 1998 vanden plas xj8 i had to replace the battery and gas pump then one day the RPMs did not exceed 2.5 rpms i seriously paid for two catalitic coverters thinking that thats the problem.....nope no luck they pulled out a P1000 code can anyone help restart the computer somehow someway

 

Interesting first post....so, you replaced the battery, put in a new fuel pump and here it is a couple days later and now you can't go over 2500 rpm's. Then you threw some mud at the wall to see what would stick, i.e. the new cats, and not only didn't it stick, now you have another issue.
So a Jag P1000 can be:
-The On Board Diagnostic (OBD) monitors are performed during the OBD Drive Cycle. P1000 is stored in continuous memory if any of the OBD monitors do not carry out their full diagnostic check.
-If DTC P1000 is triggered after DTCs have been cleared, all engine management OBD diagnostic monitor drive cycles have not been cleared.
- Battery or Powertrain Control Module (PCM) had recently been disconnected.
- An OBD monitor failure occurred before completion of an OBD drive cycle.
- PCM Detected Trouble Codes (DTC) have recently been cleared with a scan tool.

Who pulled the codes? Could they have inadvertently disconnected the code reader before the scan was completed. That being, they didn't return the key to the off position before removing the scanner.
Here's a link to a Jag bible...JagRepair.com - Jaguar Repair Information Resource ...use the Site Search for your year an model and I believe there are 3 or 4 TSB's for the 98 that involve the throttle body.

 

Try a hard reset. Disconnect the negative battery cable and touch it to the positive post for a few seconds. The engine will rev high at startup and then settle doen.