Welcome to the forum.
Are you sure it isn't something as simple as the gasket for the pump basket lid leaking air somewhere? For air it only takes a tiny, sometimes almost invisible leak to let enough air in to mess things up. This could also be the reason for low pressure. Clean the gasket thoroughly and coat it with a good silicone lube....Jacks or equivalent. Available at most pool stores.
Not sure what you meant by this statement.....'After I turn my pump on and back off there is so much pressure I can't even get the lid off the pump basket.'

Al