2.0 nissan serena running bad and cutting out when warm any ideas ??

when i bought the serena it was making a weird noise i found out timing chain had gone so had that replaced. It was still running bad so got someone to plug it into machine which told us nothing. It runs o.k when cold but once it warms up it goes bad so i tried changing lamber sensors and that did nothing. An auto electrician had a look but couldn't work it out any ideas