4L60E shift delema

[jon_bowtied_jeep]

i have a 1994 chevy suburban 1500 with a TBI350, 4L60E transmission and NP241 'case. the truck stoppes shifting into second gear, it would run up to the rev limiter all out as it usually did in first, then i'd have to back off and let it grab third, completely lacked 2nd gear. i saw several threads on different forums about shift solenoids and the like but i'm not too informed on the electronic shifting transmissions. so instead of playing with the one in it i took a known solid transmission out of my 1994 gmc jimmy 4wd just switched the tail adaptor, used the torque converter from the burb and just replaced the pump seal so it wouldn't leak. after reinstalling everything and filling the trans we took it for a test drive before putting the y-pipe back on and it ran and shifted wonderfully. i was very careful about all the wiring harnesses in the area of the exhaust and checked them well to make sure they were well clear of the exhaust system after reassembally. i put the exhaust back together with new donuts, studs, and hardare. after completion i backed it out of the shop and took it for a ride down the road. the truck will not downshift into first gear now and feels like it's always starting from second. after returning i was going to back it into the shop and now i have no reverse. now that i told you how i got here, this is where i'm at. park acts as it should, reverse feels like neutral in respect to hat the transmission does, in neutral it loads up as if you were on the breaks and attempts to push the vehicle forward but does not have the power to actually move it more than a couple inches. the rest of the gears, OD,D,2nd, and 1st all act normal but it never shifts into first. i can drive it down the road but from a stand still it revs to 3000rpm and holds there as the vehicle steadily accelerates similar to a slipping manual transmission clutch. i don't where to go next, could it be in the vehicle wiring? in the transmission solenoids? a component failure within the transmission or torque converter? any insight would be appreciated. sorry for the novel but i like to be specific. thanks anyone. -jon-