dt1608

just joined tonight . i drive a 2001 rx300 mark 1 which i have owned for 2 years . i converted my car to run on lpg which makes the car more affordable to run .Recently my brake seem to be pulsating when coming to a stop or slowing down ,brakes and disc have been changed 6 months ago but this problem started recently took the car to dealers they think its a mechanical problem maybe the abs pump . no fault lights are showing up on dash. any ideals ? would be appreciated . thanks