I have a 2000 Cherokee Sport with about 103,000 miles.
It is running great with no major problems.

Back in June 2014, I had 2 engine codes. P0700 and P0740. It was running fine, though I felt like it was going thru anti-freeze faster than normal (though the weather was heating up).
I brought it to my trusted mechanic (he also has a cherokee) and had some work done:
1) Transmission Inline Flush, including a flush of the trans & torq convertor @ $106 (for labor)
2) Trans TCC Solenoid @ $386
3) Trans Filter Kit @ $40
4) Lucas Trans Additive
5) Over Flow Hose @ $20

A month later, the engine light came back on ... with P0470 again. A few days later the engine light went off on its own. The jeep was running fine so I let it go.

Now, 5-6 months later, the light is back. The jeep went up to Maine for Thanksgiving (about 380 miles) ... on the way back the engine light came on. It was running smooth, no problems.
The P0470 code is up again.

I had the code cleared ... and I am hoping that it does not come back ... but I am thinking something must be amiss for the same code to reappear,
Any suggestions as to what I am looking at?

 

That's a torque converter lockup error. Might take a look at the brake pedal switch. (it unlocks the TCC)
Did they power flush the trans? If so, before or after changing the solenoid?
What fluid did they refill with? (Dex/Merc is correct, ATF+ is not)
No comment on the Lucas.
Keep an eye on the antifreeze levels. 0331 cylinder head and all..