Does it have a multi-arm spinner to spread the water around? Check by running it for very short periods to see if it's spinning. If not, then the flow into that part is low or non-existent. This will cause the soap not to be dispersed, and the general suckiness you describe. There's probably a filter or screen in the bottom part that is clogged. Or, could be the pump is bad or worn out.
Does the washer drain at the end of the cycle? If so, then you should concentrate on finding and cleaning the filter/pump intake. Usually you can access this by disassembling the spinner in the bottom. The center bolt-like thing is probably reverse-threaded. Once that is removed, the spinner/basket usually lifts off, and you can go from there. You may need some torx screwdriver tips to remove screws to expose the guts.
I have found exploded-view diagrams found online on parts-selling sites helpful, but they aren't a step-by-step guide, so you have to have a little faith and dig in.
Also check to see if the upper sprayer is supplied via a tube from below, you may need to remove and clean this tube. The tub can be flattish and fit snug against the back wall. The sprayer arms have holes that can clog up as well, from water minerals and fat, or other debris. Kinda gross to clean it but if you can, you'll save yourself some $$.
Hope this helps a bit!
