Hi, i had a problem with my 99 ironman that was kinda similar to yours. after changing the fluid of tranny and tcase in an express lube i saw leaks all over the pan and mode switch cover, i kept driving it for a couple of days then all of a sudden started kicking while shifting 2nd to 3rd. took it back to express lube, they said they topped it off and change the gasket. it was still leaking from the shift selector shaft(mode switch attached to one end and the other end goes inside the main case to the side of valve body connecting to an arm piston thing), they replace its gasket with the one i bought from local isuzu parts. next day was kinda warm day that i drove it for almost 3 hours in the city, sitting there waiting for green light pressed the gas pedal, nothing , like its in neutral, no froward in any gear. pressed the winter mode and started going forward. ok third gear engages(winter mode), truck moves forward and speeds up, but nothing in normal drive mode. i called the express lube and told them that they are bunch of retarded and stuff like that. i decided not to let any body touch my truck but me. so started doing a lot researches and readings, went through many connections to start, making sure there is no electrical involved. dropped the pan, dropped the valve body(someone had some work done on it or better say he screwed it up) the valve body was over torque tightened, checked the brake band solenoid by a digital multimeter, it was like 0.9 ohm over specified, that was another possibility. made a piston compressor at my work(i work as welder) to compress the servo piston after uncovering it. the piston looked good, the rod wasn't in the right position the wrong end was looking up. anyhow put the servo piston back and adjust it to specified torque(4.5 Nm. not sure at the moment) changed the gaskets with ones i got from local isuzu parts. after searching hours i found a website to buy a single brake band solenoid for 40$ plus shipping. checked the resistance of the new solenoid it sure was lower than the stock one.so i put the new solenoid in there put new gaskets new drain and filler plugs, filled it out with dexron III, followed the fluid change procedure, while moving the lever through all positions i felt the lock up as soon i put it in drive and 3,2,L. and i have done all this in our appartment parking lot(kids playing around people passing by. that sux man). called my girlfriend to get dawn and hop in, and that was it, no problem anymore.