1987 Ford F150, automatic, 5.0 v8, 121k miles.
I had some fluctuations in the rpms while driving a while back and the mechanic replaced the throttle sensor and that has gone away. Recently, it’s been having high rpms, between 1400 and 2000, after I drive a few miles to work and put it in park. I noticed yesterday and tested it again this morning that if I just tap the accelerator before or after parking, it idles at the normal range of 600-800 rpm. Before I took it to the mechanic, I very thoroughly cleaned the throttle body (it didn’t have much build up anyway). Any ideas what might be causing it?