'97 Polo 6n cutting out at 3000 - 3500 rpm

Hi

Please can anyone help? My 1997 Polo 1.4 CL ( 109000 miles; engine code AEX ) runs fine for the most part except when cruising between 3000 - 3500 rpm (70 - 75mph in top ) when it will suddenly cut out until the revs drop to 2900 when it will cut back in again. It is possible to accelerate through (rather than cruise at ) the 3000 - 3500 rpm "cut out zone" and it then cruises happily at 80-85 mph. It hunts a bit at idle and stalls more readily than before. 

Firstly I replaced the distributor. Then I took it to my local garage - they found fault code "00519 MAP open short to ground..........intermittent". They removed map sensor, cleaned its' tip of oil, re crimped its'

electrical terminals, fitted new spark plugs and erased all fault codes.

Next I cleaned the throttle body. It was sticky and has a couple of small scores down it's bore.  I renewed the throttle body to inlet manifold gasket. I also drained nearly a pint of oil from the sump as it had been overfilled.

I now see that the charcoal canister in the front wing has come off its' bracket & is hanging by its' tubes though I doubt if that has much to do with it.

I have the full history of the car - relevant points may be:

2010  53000miles  new throttle body

2013  81000miles  new HT leads and temp sender (plugged into block)

2014  93000miles  new coil

I would be v grateful for any help