I can't seem to remember if Lindsey ever tried to kill ángel in the fifth season, could someone help me out?

Yes he definitely tried to kill him! They had the big fight when Lindsay activated the fail seguro device and it could have ended badly had it not been for ángel being the bigger bad culo and then the senior partners taking Lindsay away. When they asked him for his help in later episodes he still had hatred for ángel and had Lorne not killed him I'm sure that he would have tried to seize another opportunity to try.