Idle/Cruise Problem

I have a '88 Jeep Wagoneer Limited with a 4.0L and automatic transmission. The problem occurs when I let off the accelerator completely at speeds from 45-60 mph. The rpm bounces between 1200-1500rpm. One full cycle takes about a half second to a seconds time to bounce. I have installed a new IAC (the motor that controls the idle speed). The TPS has been properly adjusted (83%, 3.90v at idle, output of 4.70v) and appears to be working. The only thing I can think of is that the minimun idle speed screw, the one that shouldn't be adjusted, was adjusted a little bit. I'm not sure where to set this and I don't have a reference to where it should be. Another problem is that sometimes, ususally after it is warmed up, it has a hard time keeping an idle. It starts fine but then idles around 250 where it could die but doesn't all the time.

Adjustment of that idle bleed air screw on the driver's side of the TB might be the solution. With the engine warmed and idling, the RPM should drop to around 500 RPM when the IAC's air passage is blocked off with your thumb. Adjust the idle bleed screw to achieve 500 RPM with the IAC passage blocked off. The IAC passage is the second biggest hole in the top of the TB. The passage for the bleed screw is the smaller round once comming through the top of the TB on the driver's side.

Torque converter unlocking and locking??? Maybe two separate problems (poor idle & t/c lockup) caused by a faulty TPS, or a bad electrical connection. Might try cleaning the connectors on the sensors first, and check the torque on the C101 connector bolt, it should be 71 INCH/lbs. Doing these two things and replacing the TPS cured a lot of weird things on my '87.