car running like kack

[adamgte]

When i put my foot down the car accelerates a bit then slows and does this back and forth untill i reach the end of the gear or when it reaches high revs somtimes the problem stops. Doesnt really do this in 1st but at worst im been in 4th at full throtle and the most it can reach is 70?! In the mornings on the way to work when the engine is cold, it runs fine with no problems at all? Also it was cutting out on tick over when sitting in traffic, even with the tick over at the highest mark, so i have had to bodge this open a bit futher with a cable tie to keep it running. Thought about having it tested on a rolling road if this would help. Also its a 1600 gte.
Can anyone one help with this?
Thank you