Your rear shock is shot and it's an expensive one. The Swedes decided that that independant suspension needed to be self-adjusting, so they put in some Novamat shocks that would pump up the suspension when loaded. The biggest problem is that on that model there is no aftermarket replacement and the best price I have seen is about $250 EACH for those bad boys. The earlier Novamats could be converted, but I haven't seen any solution to these. I would love to find an air shock that would bolt in and repair that problem (mine has it too) but so far no luck.