04 GT N/A 65K "no CEL"
For several months now I've noticed the car bog down to 300 RPM then pop back up to normal - sort of a hesitation or hiccup - at idle only when I was coming off the freeway to a stop. Didn't happen often and only 1 or 2 "hiccups". Idle never went high, always bogged low.
I changed the wires and plugs recently and added a HAI as shown in some posts on here with PVC and couplers from Home Depot. After these changes, the car ran better but problem still persisted.
In the last week, the same problem is becoming more frequent and now it's happening at any time, not just coming off the highway. And sometimes the idle will go down a dozen times in a row. It hasn't died, no problems starting, and no power issues that I can tell. When I go WOT everything seems fine.
Then only other thing I've noticed and I can't put my finger on the timing is that I'm getting pretty lousy gas mileage. 18MPG in the city with A/C running. I don't drive it hard. I drove it out of town a couple weekends ago and got about 26 on the HWY. 93 octane gas. Tires at 35psi. It does seem that I noticed the drop in MPG about the time I installed the HAI although that was also the time that I started paying closer attention to it - so not sure...
I don't know if this is one problem or two but I wanted to provide all the info I have.
I ordered an O2 sensor and fuel filter from rockauto and should have that installed when it arrives.
What else should I be looking at?
Thanks in advance.
