I blew the HG on my MK2 8v punto just over a month ago, had that and many other gaskets replaced and since then i am having many issues with the engine.

The engine light on the dashboard keeps popping on, sometimes accompanied by the oil light. On one occasion the engine idle speed was 3000revs, and another occasion the engine only ticked over if i pushed the throttle pedal down. The engine error codes are P0120 - throtle pedal position sensor and P0340 - Cam position sensor.

any ideas on what the issue is or what i need to replace?

well to me the obvious things to replace would be the parts throwing up the error codes, the throttle position senson and cam sensor, and see how the car runs from then on