2000 ford explorer lift gate

It may (VERY likely) just need a new rod clip-the one that holds the horizontal latch actuating rod in place. If the clip still looks good, get a new one and keep the old one for a spare, because its liable to happen again (at the worst possible time) if you reinstall it. When that rod comes out of the clip, or the clip breaks, there is nothing connecting the door handle to the latch mechanism, which is why the handle has no back pressure when you lift it. A lot of those clips used to be plastic and eventually broke.

Its very likely just the clip that connects the horizontal latch-operating rod. If the old one is still in one piece and looks good, don't make the mistake of reinstalling it, as it will probably fail or come open agian soon-usually that happens at the worst possible time.

If I bring my car into a shop how much should it cost me?

I went out yesterday to see how hard it was going to be to open the panel and just decided to try and open latch and it worked?! What in the world is that all about?

It sounds as though the latch mechanism itself was stuck in an "almost released" position. My best advice is to make sure to lubricate the latch mechanism-the metal parts that you can see in the side of the liftgate when its open. (White spray lithium grease is usually used for this.) Spray it, IMMEDIATELYclose and open the liftgate a few times, then spray it again. A one second spray or so is enough the next time you remember to do it, -and a can will last for years. You'd be advised to do ALL the door latches and hinges and door hinges, when you do this one. This is supposed to be done about once a year-and would typically be done for you if you take the vehicle in for regularly scheduled service at a dealer, but VERY few people do it AT ALL once their vehicle is out of warranty.