I have an '85 Eldo with only 24k miles. Nice car and one of the only HT4100's I have ever driven with a correctly working throttle and idle. Smooth and progressive with no delay. Unitl now. The car is acting like all other HT's. I presume it is the nototious TPS sensor since the idle is still good. No codes, but then again other HT's that had terrible throttle response never threw a code either.
The TPS is an electrical sensor(potentiometer) that measures the throttle-valve angle. It can be out of adjustment, Open, or Shorted. When Open or shorted it should set an E code(E22/E21). Before laying the blame on this piece verify there are no vacuum leaks at the throttle body/intake manifold/vacuum fittings/tees or hoses. Your description would lead me to first check the vacuum system.