engine not reving properly

hi everyone i hve  problem nd tht is tht my engine will not rev further than 3-4 thousnd rpm nd i ws just wondering whts wrong with my car. it sys in the hynes mnul tht it is rust contmintion is this true nd if so is it expensive to fix?

I had something that sounds similar on my polo , it ended up being two of the HT leads had been swapped over !

When you say rust contamination do you mean in the fuel tank? If so that'd cause the car to stall/not start/basically starves the car of fuel intermitantly.

Does the car rev freely in nuteral? All other guages normal (temp etc)?

Check for obvious stuff first
Throttle cable is tight and hasn't come loose
Check HT leads are in good nick, no cracked/damaged
check dizzy cap has good contacts/good order
Check all engine earths, the one under the battery attached to an engine mount is a particular one prone to rusting