I bet if you switched out the pump with a replacment unit, your problem would be solved.

If so, then you are either low on fluid or the bomb is on the way out.

But that still does not explain why the steering is heavy...

Check your hydraulic fluid resevoir, you have to use a mineral based hydraulic fluid on these cars, possibly someone used the garden variety power steering fluid in your car. If that is the case, both the PS pump and the rack will be toast in short order.

Is the hydraulic resevoir up to the full mark?

problem was a little better

also check for belt tightness and condition
mine did that with an old skweelin belt.