Lately my car has run rough and has had a wacky idle, first just on a couple of really hot, humid days, and then today it was worse than the other days. It seemed like it was about to stall at some stoplights.
Lately it has felt weak under light throttle and throttle response has been lacking. Even under full throttle, when going uphill, even slightly, acceleration felt weak.
First I replaced the fuel filter. That seems to have helped with the weakness, but the car still felt like it was about to stall.
Under the advice of my girlfriend’s dad, I loosened the gas cap. Sure enough, it runs and idles pretty much fine now, although it still feels a bit on the weak side. I’m quite sure that the whole loose gas cap trick is just a temporary fix.
With that in mind, and from what the Chilton manual says, it is most likely that I have to replace the fuel pump. (hopefully nothing else)
There seem to be other things to check/replace/etc. from other similar postings here.
Has anyone else had this exact problem, and fixed it by replacing the fuel pump? Is the fuel pump easy to replace?
The fuel pump is in the trunk pull up the carpet and then you will seee the sending unit it is in there …i dunno if thats your problem though
Thanks. The Chilton manual was kinda vague about that; it gave a few diagrams, and said that some of the cars needed the fuel tank to be dropped to get access to the fuel pump, and some didn’t, but it didn’t specify which.
For rough idle, it lists fuel filter (just changed it), air filter (checked it, it’s fine), and fuel pump.
My girlfriend’s dad had seemingly the same problem on a Ford van he used to have, and unplugging the gas cap worked. When he took it to a dealership to find out about a more permanent solution, they wanted to replace the entire fuel system (and they wanted $2800).
I really hope this isn’t that bad.
Also, if this helps narrow it down, I’m pretty sure I also have an exhaust leak, since it backfires when I let off of the gas while I’m moving in-gear. That will be fixed once I put the header on, since I know the catback exhaust and cat are fine, and that the current exhaust manifold is only being held to the engine by 6 bolts instead of 8. So fixing that leak should fix the slight sluggishness.
I retightened the gas cap, and it ran fine all day today, I had like 20 deliveries too. Strange.
A couple people have told me that if the fuel pump needed replacing, the car would run really shitty (which isn’t quite the case) and I could really, really tell.
Maybe replacing the fuel filter and running with an open gas cap helped something which was clogged pass right through the system? 
if your car still bogs on acceleration you can also check your MAFS, maybe it’s dirty.