Toyota Repair: 86 celica GTS, fuel pumps, intake tube

Question
It hesitates while in gear/accelerating but idles fine. I have found it happens sporaticly more when the car going up a incline. It stalled out completly once but was able to start it latter with no problem and drive away without any hesitation. it takes a few cranks to start in the morning. Slight hesitation if you stomp on the gas while idling. I have changed the fuel filter. the car has 230,000 km. the fuel pressure at the manifold was 1.5 cm/3. Is it the pump or something else. If it is the pump why would it work on and off. Fuel pump is expensive. I want to be sure before i go there. Any thoughts on this?

Answer
Fuel pumps normally fail completely all at once so I don't think it's the problem, it sounds more like there may be an air leak on the intake side, a common cause is the large intake tube from the air cleaner to the throttle body, check it for any cracks or looseness at the clamps.