hippchip

So a year ago or more I had an air strut fail and decided to convert to struts. I found a LS430 with struts and springs at a junk yard and had them deliver the struts and springs to my my mechanic. This guy did the conversion on my LX470 with no issues. Even though the struts seemed perfectly fine I purchased new sport struts from Lexus and had them replaced. They lasted a few months started leaking and failed. The Lexus ppl replaced them but said this would be a one time thing. The next ones also failed. I am wondering if I am missing some part or something. I am not sure if the junk yard sent everything that was on the unit they removed the coil struts from so just dont know. I dont have any lights or anything like that just after the struts fail my ride is terrible. bouncy botttoms sometimes. unbearable. I avoid driving the vehicle if I can help it. Looking to fix it but dont want to replace struts only to have same thing happen again. Any ideas???