Replacing accuater pin on a 89 f150 - 1989 Ford F 150

double anon posted, why?
back up and read. answsers in your post 1

F150 is a Ford model truck, not GMC.
But at any rate, since I don't know if you have a Ford F150 of some kind, a 87 GMC S15 or some kind of 89 GMC with a V6 I will suggest taking the ignition module to an Auto Zone and having them test it (A free service). Also test the fuel pressure.
If a tune up and fuel filter has not been done in some time that could very well be an issue.

remove brakin system(caliper pads rotor) then disconnect outer tie rod, remove cotter pins on both ball joint nuts and remove nuts, then separate hub from i-beam, on the bench remove spring clip holing ball joint and press out, press in new joint and install hub in reverse order of dissassembly, apply grease to axle regrease bearings and caliper sliders, you will need a ball joint separator and a ball joint press, use new cotter pins

You only need general tools. It is located beside the throttle body. It would be much easier to take off the throttle body first.

35-45 psi

the first thing to do is to have the trany computer scanned for codes, the code will help alot in pin pointing your problem,you can try autozone they scan for free, these trucks that ive worked on.one had a bad 4wd transfer case selector motor, and another had bad front wheel locking hubs, these hubs are vaccum operated and go bad often the diafram rips on most of them.

sounds like the accuator on either the t case or front diff

SOUND LIKE FUEL FILTER STOPPED UP.

Sit up on the clutch paddle, follow the clutch paddle up under the dash, the rod that goes through the fire wall to the clutch master cylinder, sit around that rod, will have a six pin connector going to it.

check the switch under the hood. right hand side on the fire wall just under the wiper cowl. this happened to me. ford says water from the wipers leak on the switch and shorts it out. they replaced the switch and losely put a plastic over it to keep the water out. make sure not to put the plastic too tight, it is vacuum , so it needs to breath. Also check the front wheel accuators that engage the front end(next to the wheels), ford had some bad accuators that would not hold the pressure this to also happened to me. ford should pass it on a goodwill warranty. hopefully nothing else is broken. cost me $500 because i damaged the wheel bearings. ford won't pay for those.