Every time I turn my A/C on my truck the RPM goes up and down

Most likely not. Look for any vacuum leaks first. If all ok, I would look at the iac motor. It may be bad.

Roy

Yes, along the intake manifold. You may need some help if you are not familiar with this operation

Roy

First check to see if the A/C is cycling as fast as the speed variation, if it is only doing it in conjunction with the A/C on I doubt that it will be a faulty IAC.

Sounds like the throttle body sensor, Under normal conditions when the engine is running each time the air conditioning kicks on there will be a drop in idle speed. This is caused by the extra strain on the engine. When the compressor shuts off then it should be normal. As far as the reving up, have found that the position sensor can make the truck do that.

In what order did you re attach the battery cables? Did you check the ground wire pigtail if it has one? If it was damaged, or broke off the fender, re attach it too! Try disconnecting the battery for at least 5 minutes, remove the negative cable first, and put it back on last! This will clear the KAM, Keep alive memory, and you can now do a new relearn.

OK keep me posted.

OK, you might also want to check the rubber PCV elbow, they tend to dry rot and allow vacuum to escape, try replacing that too. Ford has a good supply of these on hand. It's a well known problem!

Is the check engine light on? Autozone can read the codes if any and they do it free, Post all codes found.

The IAC is a common problem on these anyway, get a can of spray Throttle body cleaner, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody
Clean out the throttle body too. Do it with the motor off, and use a rag to wipe the carbon off with the tbi cleaner. If this has the electronic throttlbody, there is no IAC. Clean the throttle body, it may work, taking it off to clean will yield better results! Ford states these throttle bodies are not to be cleaned. Think Toyota here. Electronic throttle control is tricky stuff, NASA is involved with figuring out Toyota's problem, so you really do need to be a rocket scientist nowadays! BTW which engine does this have? 4.6, 5.4? Be advised, using cleaners not meant for throttle body cleaning WILL KILL etc throttles. If it stalls at idle, but runs good, it's probably the electronic throttle actuator.