2001 trooper code P1870 runs about 20 miles then trans starts slipping like you shifted to neutral after it cools good it will go about 20 again what is problem and what to do to fix it?

the cooler is plugged, trans over limit temp. hope front pump is not smoked

7j7, ...and what to do to fix it? finish this now, you've started it-

P-1870 means "Transmission component slipping". A very common problem with these transmissions which sets a P-1870 is 2 valves in the valve body, the TCC regulator and isolator valves. The reason for the problem is these valves wear out their respective bores, the converter clutch apply oil passes by the worn valves lowering the apply pressure of the converter clutch. The clutch then starts slipping and chattering, sets a P-1870 and maxes out the line pressure causing harsh shifts. The way I usually fix these is with a kit from Sonnax. The valve body is removed, both tcc regulator and isolator valves are removed, their bores reamed, sleeves installed with new valves. This is what needs to be done and will cure 95% of P-1870 issues.

bob_nueske where can I get a sonnax kit? also what do I ask for? thank you very much.

https://www.google.com/#q=kit+from+Sonnax.&tbm=shop

bob_nueske is the feller from Wittenburg, WI that I buy my tasty smoked bacon from....no other...to die for, but out of respect I switched to juge_roy...of course a lowercase J because, I'm not a REAL judge...just a dude who's excellent with these machines~