'94 f150. my rpms will sometimes be at 1000-1500 and jump up to 2500 and then go back while im driving. this has happened a couple times. i know the guage isnt broke becuase i can feel the truck lose and gain power. it only has 62,000 on it. is the tranny already going bad. i think my altinator is going bad too becuase sometimes my truck wont start and or it'll idle at 500rpms or lower. is there a connection between the two or just two different problems. any ideas?

 

That hurt my head...You can start by checking all of your grounds coming off of the Negative (-) side of the battery. I believe there's a very important grounding point down on the passenger side frame rail toward the front, but you can also just follow the wires coming from the terminal on the battery. If those are in good shape, check your voltage with a multimeter at idle, it should be 14.4v (+/- 10%) so if it's below that, it could be your altenator, or possibly your battery.

As far as the wandering rpms, you can start by checking your TPS on your throttle body. It may need cleaning\adjustment\replacing. It's a little more in depth, so let me see if I can find a link. Here ya go: http://fordfuelinjection.com/?p=30

 

Which transmission??? If you don't know, read this caption:



It couldn't hurt to clean, inspect, & tighten/replace the battery terminals as described in these captions:

 

it says "E"

 

If your tranny is the EOD4 (overdrive) try replacing the neutral safety switch. My 94' was doing this at about 77,000 miles. It would act as if it kicked in and out of gear (which it was doing) while I was driving. After two tranny shops and hundreds of $$ spent on BS a fellow here pointed me to the NSS. Problem solved...