1991 Cadillac Seville Car has hardly any power/terrible gas

I have a 1991 Cadillac Sevile w/ 183000 mi. I've changed the plugs, wires, cap, rotor, and ff all recently. I recently filled the tank up, and the car started acting up. It hardly has any power(I have to tramp the pedal to the floor to make it up a hill) and of course the gas Mileage has went down to almost zero. I changed the fuel filter again, put some injector cleaner in it (along with some dry gas) and refilled the tank. Same result. Almost no power. When I step on the gas, it basically has "no go". I have 3 engine codes: Throttle body needs cleaning, interrmittent map, and throttle body int (?) I had this same loss of power problem a few months ago, then I gave it a tuneup and it all went away till now. It does need a new muffler (hole in it) but I didn't think this would cause it since the muffler problem has been ongoing. Oh, one more point: the fuel filter I had recently changed came out not blocked, but a rusty color fuel from it. Thanks for the help!