Hey UK,
Welcome to the boards!
Near as I can tell, if you have the 'H' code engine, it runs 155 horsepower. These cars aren't much off the line, but once you're cruising, they're fast enough
It should have a catylitic converter, and an O2 sensor. Check your exhaust manifolds or the end of the crossover pipe for it. It can cause drivability issues, basically, it will tell your engine to run rich or lean.
These are heavy, comfortable cars, and I can imagine trying to manuver(sp?) such a vehicle through your roadways. It must be fun trying to find a parking spot
If you would like to stiffen the suspension, I would recommend looking into finding parts for the same model police vehicle. The police vehicles had a heavy-duty suspension and brakes, making for a better handling, better stopping, and over-all more responsive car. (they also had more powerful engines). Maybe look into adding an anti-sway bar and/or polyurethane bushings? That would definately help.
Enjoy your stay here, sometimes it takes a while to get a response so keep checking in......