Thanks, this is the one I queried about. £1560. Cheers.

 

That's a stupid price....
For that money I'd buy a second hand throttle body and have it reconditioned by someone reputable. Ie ASI. Then make sure you calibrate it properly before refitting.

Lets be honest here, nothing you do going forward will get you your money back from what you've done already. But that's no reason not to go back to basics and work your way through one item at a time.

Where are you located? Maybe you might be able to find one to borrow or swap from a wrecker or something?
There are probably a few forum members with old parts lying around too. I know I have a spare throttle body sitting here... but mine's from a 2000 with the electronic cruise control, not the vacuum operated one, so it's no help to you

 

Is it not the TC failing?

Why not watch OBD values...

 

If the car is throwing a lot of different codes, it usually points to a dying battery. These cars are VERY fussy about having good voltage. Check that the alternator is putting out the right voltage, (14.2-14.4) Check that the voltage at the battery is almost the same as at the alternator. If not, clean all the connections between battery and front of car; there are a lot of them. Also clean the two earth cables; the one from the battery, and the one between engine and body(underneath). If that doesn't fix the problem, bite the bullet, buy the proper battery for the car, charge it fully before connecting. Keep us informed