Baxi 105E Central Heating Hot water goes cold Extra bits?

Baxi 105E Central Heating Hot water goes cold?
I have a Baxi 105e Central Heating combo which when you turn the hot water on it goes hot and cold, general heating working fine pressure dial when cold 1.2 bar, When you turn hot water on Yellow led comes on temperature heats to 60 degrees c. Then boiler switches off. About 5 seconds later it relights and goes to 60 again, This is continuous. Have put a new diaphragm into DHW pressure differential valve. Old one has small split. When you turn the hot water on inside the boiler the micro switch on the DHW Pressure valve the prong comes out and switches it on, at the same time the micro switch on the divert manifold does the same thing. When the gas goes out and water runs cold the micro switch on the diverter manifold goes in and then out again
When water is running hot the flow pipe on the central heating, is hotter than the hot water pipe.
Hope someone can help tried to include as much info as possible.
Cheers, Andy
PS fed up of cold showers
Do a bit of plumbing myself so quite handy just need pointing in the right direction.

Firstly thanks for all the replies before when i listed it because they were all different called a boiler repairs man out, he to was unable to fix it but we now a bit more about the problem.

It would seem like something is turning off the pump which is causing the problem, flame goes up and down when temperature is changed on hot water, pump works fine on central heating, whilst here the engineer checked the switches with a meter these seemed to be fine, also tried a new pcb board but the problem was still there, don't now if this spreads any more light on things this seems to happen if the water is on and temp lights get to 60, no flashing lights.

long winded i now but every little helps thanks for reading.


__________

central heating Aberdeen
combi boiler Aberdeen