i have a 1986 ranger 4x4 with 2.9 6 in it. It has 143000 miles the prob is rough idle bad skipping and hesitation when going a steady speed if i hold that speed for about 30 secs it will clear up and go fine it accelerates as if still new also some iratic shifting it is auto. i have replaced plugs, wires, cap, ignition module, rotor, distributor and map sensor someone please help any suggestions will be nice

 

Just a couple of items...

When were the two fuel filters replaced last? You have a low pressure cartridge filter and a high pressure filter. The high pressure filter is on the frame rail under the drivers feet and the cartridge filter is in a black canister back a little ways behind a steel plate (should see three fuel lins connected to it).

You could also have a failing TPS sensor causing erradic fuel delivery.

Also, pull the vacuum line off of the fuel pressure regulator to make sure that there is no fule in the vacuum line. If there is, the regulator diaphram is failing/failed.