not running on all cylinders

[daren parker]

when i first got my car the engine was holding back up to 2000 revs ,so it was looked at at a local dyno center .the vacume unit,leads plugs were changed ,the injectors were removed and cleaned with a ultra sonic machine .the holding back problem was solved but i have a new problem .the car does not run on all cylinders bertween 1000 and 2000 revs ,and worse up hill when there is load on the engine .after 2000 revs the car is fine .any ideas thanks daren

[K4000JB]

hi daren
sounds like it could be the cap rotor arm or coil braking down under load i would change the cap and rotor first but only use lucas ones as the after market ones have caused some probs and if they dont solve the problem you have some useful spares
cheers
ant