sudden gas mileage drop

[AtlanticCobra98]

I have been getting around 220-230 a tank and i did a tune up new air filter and new spark plugs and now im getting around 130-150 a tank. No codes other than for rear o2 sensors. here are the plugs i put in. gapped a .054 i believe. Where should I look for the sudden drop?
NGK G-Power Platinum Performance Mustang Spark Plugs 3403 (93-01 Cobra; 96-04 GT, Mach1; 98-04 V6) - Free Shipping 3403

 

[AZSN95SNAKE]

I have been getting around 220-230 a tank and i did a tune up new air filter and new spark plugs and now im getting around 130-150 a tank. No codes other than for rear o2 sensors. here are the plugs i put in. gapped a .054 i believe. Where should I look for the sudden drop?
NGK G-Power Platinum Performance Mustang Spark Plugs 3403 (93-01 Cobra; 96-04 GT, Mach1; 98-04 V6) - Free Shipping 3403

Did you actually gap them? or were they "pre gapped"? If you didn't gap them, pull them out and gap them correctly. Did you reconnect the intake correctly and plugs on it? (I take it you know what you are doing btw, I hope I didn't insult you as that's not what I meant to do).

 

[AtlanticCobra98]

I gapped all of.them before i started. ill re-check everything again. No offense taken. everyone messes up so questioning the basics is always a good thing

 

[Fox 5.0]

Is it just the gas mileage that was affected? Does the car feel sluggish or anything like that?

 

[AtlanticCobra98]

no everything seems fine. a few times it felt like the imrcs were not opening but it seems like they are now. it was sputtering really bad from 32-4k. This was a few fill ups ago though.

 

[97ReoCobra]

Are the spark plugs identical in brand and heat range to the plugs you replaced?

It would be far more accurate to actually calculate your gas mileage rather than guestimate how many miles to a tank of gas you get.

 

[AtlanticCobra98]

i do. i went from 18.5 or so to around 10-10.5 i forgot to add that. I think i may have found the problem though. The iac sensor was twisted so the sensor was being blocked by the the plastic piece on the side of it. It seems to be running better.

 

[97ReoCobra]

i do. i went from 18.5 or so to around 10-10.5 i forgot to add that. I think i may have found the problem though. The iac sensor was twisted so the sensor was being blocked by the the plastic piece on the side of it. It seems to be running better.

Glad you found the problem. And the fix was easy and free. Can't beat that.
I get 22/23mpg with my stock 97.