I just bought an 1986 ford ranger. it has the 2.9L fuel injected motor. auto tranny. runs like a stipped ape. most of the time. I changed out the vacumme modulator on the tranny it was bad.
the problem is going slow or fast, it seems to the motor cuts out or something. doesn't completely die but sure slows down. the tranny seems to jump back into gear also. not quite as noticable when the ac is on, but still there. it isn't the inerita switch, I bypassed that right away.
back to the vacumme modulator it was bad and had tranny fluid in the vacumme line. could that have gone somewhere and caused a problem??
all i know is it is a bit agravating when it happens all the time. the mechanic in town isn't sure what to make of it either, so I thought I would ask all you out there in cyber space. thanks mark

 

just guessing; could be the TFI module [dry contact] or maybe fuel or ign. relay [low voltage due to corrosion in plug] or believe it or not, a bad battery [or dirty posts]. good luck

 

There is a recall (for 86) on one of the relays located on the firewall.I had the same prolblem on my 86.