dme relay problems

[gorgeee]

hello all
i have a 86 951.i have recently replaced the dme relay as the car wouldnt start and that cured my starting problem straight away.when i took the car for a spin it was fine until i put my foot down and let the revs build up then it cut out.and seem the relay had gone after leaving it parked for a few minutes it started and i was able to get home.since my last relay failed and the new 1 was fitted the car is ok when driving normal but if given alittle bit of work it cuts out as im trying to build the revs.it seems something is making the relay want to give up then after its cooled down its ok again(sometimes can be inbarassing if waiting on side of road to let it cool down or at lights)
please help me if theres any one that knows anything about this as i love my car.
p.s the cars been serviced and had most parts changed