I would run a can of Sea Foam through it. Take off the vaccuum hose on the top of the air intake and pour about half the bottle in the intake while it idles. Put the hose back on and let it sit 15 minutes and then start it back up and it will burn out a lot of crap in your engine. Put the other half bottle in a tank of gas and that will clean out your fuel injectors. Other thought is it is time to change your spark plugs (and maybe your o2 sensors, but I would start with the smaller stuff first).

 

There's been more than a few replies all offering good solid sound advice.....

Now hoping to hear back from the OP to see what he's done and where he's at with these issues?

 

It's probably your o2 sensors if your mileage is that bad... That's like half the mileage they are supposed to get. I'm not sure though, I thought they threw a check engine light, but maybe only when they're really really bad. Also I would disconnect your neg battery cable for like 15 minutes to reset your ecu, and afterwards drive mellow for the next week, and your computer will relearn your shift points and fuel maps. I would also replace the fuel filter if you haven't done that yet.

 

Update--\
---------------\
The car got a tune up not long ago, haven't checked the o2 sensor nor fuel filter.

air in the tires is even now, the psi's were all over the place 45,30,32,33 nw they all 33. What has helped a little with the MPG's is not letting the car idle and let it warm up as I go. I used to let it warm up for five minutes. I'll take it to the shop later today there's a vent connected to the air filter that is broken I'll post a picture later, I think this might affect my mpg too.

Many great solid advices here I'll update you guys later

Thanks for all the help.

 

Another thing is you can do is get a can of mass air flow sensor cleaner and clean the little maf sensor in your air intake tube. If that is dirty, which it probably is with 100k miles, it can decrease gas mileage.

 

My 2.5 has read as high as 32 mpg ( Imperial ) & as low as 24 mpg ( imperial )

 

Good, sounds like you're on the right track at last for sure.

I'd still look at getting the Lambda 02 sensors checked / replaced at that mileage......they're long overdue

Of course all of the aforementioned depends on whether you intend to keep the car for a while or not?

 

I didn't get to fix the air bent thingy yesterday but my MPGs been looking good after I reset the ECU and put air in the tires. Been getting 16.6 max 17.2

 

Just for info as a ballpark.. I've been keeping tabs on my fuel use for a year or so now and my reasonably maintained X-Type 2.5 (just like Top Gear grin) manual consistently manages 21mpg with town work stop start 10 to 40mph and 31mpg on a long motorway or clear 'A' road run.