Hi!
I always fall behind in Technology.
On maso+ difficulty that's normal. For lover difficulties I suggest you to set sliders so, that you always spend about 50% of money for research (spending always at 100%, sliders at 1%/49%/50%), and to build on each planet at least 1/4 of labs. And OFC allow tech trading, push your diplomacy ability high, and go on tech shopping among AIs. Just never sell diplo tech, ground combat tech and wartech you exclusively own.
BR, Iztok