Ive got a 98 civic auto. (B4ra) came in as "drives fine for 1-2 miles then complete loss of forward/reverse engagement". Full soft rebuild (clutches, seals, orings,check *****, gaskets)and cleaned everything. Found what I had believed to be the issue, clutch pressure control valve spring was broken (typical issue with the b4ra and the likes) wasnt much clutch material or any material for that matter in the fluid so buttoned it all up, tested solenoids (all checked fine) put it back in and test drove. Same problem. Drove it 1.3 miles, shifted fine, no issues with engagement,shift points, shift feel then literally out of nowhere felt a slight slip then bam all engagement gone, both forward and reverse.turned of, Let it sit for 5 mins, turned on and it drove fine for 1/2 mile. Did it again and again half mile. Had to do it one more time to get it back

 

what gear does this problem start in? 3rd? 4th? trans temperature?

make sure the fluid is correct and filled correctly. Shouldn't have to say that.

A broken clutch pressure control spring will not cause the car to just lose the ability to move, more so a shift flare if anything. Was the unit rebuilt because of the problem?

Are there any DTC's? If not this a pure mechanical problem. Given the slippage you should have a trouble code.