Gearbox problem V90 1997

[Fred Trotman]

I am having problems where, when the engine is hot - say after 100mile journey, the car behaves as if has fuel starvation. Thats what I thought initialy. Accelerating from a standstill the car pulls back, then accelerates, pulls back, then accelerates. This carries on every 5 to 10 seconds. If I leave off on the accelerator, the car will start to settle down. With very slight acceleration, I can continue the journey but very gently. I am now of the opinion that the problem is with the auto gearbox. I am thinking this because if I select "L" on the gearchange, I can drive the car in 1st gear with no hesitations at all - up to 5k rpm without any hesitation at all.

Can anyone help on this one? Sorry if my description is a little vague but I hope I have described enough for someone to identify the problem.