With only three it will hold fine but the rear will tear quite fast and then youll be right where you are now. Even removing the mounts and filling them with Window Weld will solve your problem at least for now. Instant eurethane filled mounts, voila. You can try just the rear and see if it solves your problem.

Also if your engine is newer than 92 the driver side mount will have a lsight twist and if you get the stock replacement mounts from hasport they dont account for this, only for the original 88-91 engine. Innovative does have a mount for this though.

Again, im assuming your driving an EF...Which you are.