Do you smoke? I had the palpitations, mine were totally down to smoking
Safe limits of caffeine are thought to be 250-500mg per day. 1 cup of tea is between 85-100mg per mug. Coca cola is about 36mg per can. Coffee can be up to 210mg per mug.
Try cutting down the caffeine and if you smoke wean off them and see if this helps.
They can also be down to increased levels of adrenaline
, this can be linked to stress
(both reactions produce excess adrenaline)