[seanof30306]

Newb here

'96 Jeep Cherokee
4.0
I6
Auto

I bought my jeep new in '96. It's always gotten 16-17 mpg, with ver little difference between city/hwy.

About a year ago, I began using some hypermiling techniques to improve mileage; slowing down to 60, or less, shutting the engine off at stoplights and drive throughs, coasting up to lights and stop signs, etc.

I decided to go a step further and began shutting the engine of when coasting. Not long afterwards, it developed two problems:

1) While cruising at highway speed, the converter would lock, unlock, lock, partially unlock, etc. There was no rhyme or reason to it. Sometimes it did it as long as it was in overdrive, sometimes it did it and quit, sometimes it didn't do it at all, sometimes it did it, quit, started back up, etc.

2) From the day I bought it, it has always started perfectly, within a revolution or two, every time. Now, it starts perfectly when cold, but, after it's been run for even a few minutes, it will not restart unless I floor it, and it wouldn't idle until after it had been running again for a few minutes.

I reset the pcm, which cleared the converter problem up completely. The starting problems continued, though.

At the suggestion of a friend, I checked the IAC valve. It looked pretty crappy, so I replaced it. The starting problems remained unchanged, but the idling problem after the restarts has cleared up.

I had my ace mechanic look at it; he can find nothing else wrong, and suggested I have the PCM reflashed, which only a dealer can do. For big $$$$$

Also, my gas mileage has been steadily dropping. After beginning to use hypermiling techniques, I'd been averaging 20 mpg. It's been steadily going down, my latest tank was 16 mpg, which was where I started.

Now, I just found out the other night that all of the gas available in my area is E10, which I believe could be affecting it, but a 20% drop?

Does anyone have any ideas?

Thanks