Huub Cuijpers

Do you know anyone that could help me with the following
>
>I bought an RX7 turbo 2 cabrio new on the road aug 1990
>I bought it in 1995 when it had 60.000 km on the clock
>the car has now 80.000 km down
>it drives now 2-4thousand km /yr, and I use it with intervals of 2-3 months
>Since about 1 year I have some strange problems
>Some times it happens , some times not
>What is the case?
> One drives quietly ( 120 km/hr) at the French motorway, and you want to
> overtake, the whole motor power hampers, as if it has a hiccup. I have
> to slow down gasoline stream towards the engine.
> I drive away and the driveway , up to the road is very steep . You want
> to rev up, and while loosing the clutch , I loose power, and almost the
> engin switches off ( the revs go below 600)
> You want to use the entire power of the engine. Push the gas pedal down,
> for some times it goes well, later on the engine hampers again ( see
> first dot)
>The garage here talks about exchanging the "valve box"
>another exchange might be the whole fuel injection and dosing system.
>
>When all works perfect, the engine is still fantastic, but driving with
>these strange hiccups is no fun
>
>Thanks for any help
>many regards
>
>Huub Cuijpers