Mileage has gone into toilet -- 2001 SOHC

[bluevolume]

I've been happy with my newest Ex until a few weeks ago, when something went wrong and my mileage dropped significantly. I know this is a hard problem to pinpoint, but I'll tell you what I know.

Had this vehicle for about 7 months, averaged 350-370 miles per tank. Starting about 2 months ago, mileage has dropped to 290-310 per tank. I drive around 500 miles a week, and my routes and driving habits have not changed at all.

I've noticed that when I first start my Ex from cold the engine revs way up, to almost 2000rpm, then immediately drops down to like 700. It didn't used to do this, usually it would only hit around 1100rpm when starting. The transmission also seems to be shifting at the wrong time now, it always did this somewhat but it is much more often now.

I haven't had any CES warnings -- even scanned with a tool this weekend and there are no codes. I've tried lots of different fuel injector cleaning products, and even did the SeaFoam job this weekend (which was worth it just for the fun).

Any ideas here? I'd really like some suggestions if someone's been down this path before. I'd rather put in a second gas tank than take it to the dealer for their "diagnostic" service.

Blue

 

[IAmTodd]

Someone on here, I think it was JDraper, had a problem with his transmission and it turned out to be his thermostat. Not sure what his other symptoms were, maybe he'll chim in.

 

[bluevolume]

I'm still working through this, I'm down to thinking its the TPS or my oxygen sensors. Is there any way (without going to the dealer) to test either of these? I remember someone mentioning before that you could test the resistance on the TPS to make sure it was calibrated correctly (I searched and only found info the the OHV engine).

Any other hints would be great.

Thanks,
Blue