Eric's post makes a lot of sense. Lots of good points to consider.

I don't think you need to necessarily pick only two lifts to work for heavy 3-5 rep sets though. Training a lift in the 5RM zone doesn't necessarily mean it becomes the priority lift. Westsiders often do their heavy singles on the ME lift, then get their heavy work on the supplement lift; GM's to the Squat, CGB to the Bench for example. That said, I definately agree that some prioritization is now a necessity as Eric has pointed out.

Just as an example, here's how my ME Upper looked the other day:

Bench 3x1
Press 1x5
CGB 3x8
Chin 4x8

The bench was my main lift and the press my supplementary press. The other stuff was assisstance / accessory and thus had higher reps, lower intensity and controlled rest periods. I've essentially prioritized the Squat and Bench, with the GM and Press or CGB as the major supplements to be worked heavy that day. You could perhaps start thinking along these lines as well.

I would also agree that an upper/lower split is a better option if you want to continue training 4 days a week. Essentially you've been doing 4 full body workouts a week for a long time now. Done great with it for sure, but it's probably time to organize things a bit differently. If you want to do 4 full body days still, then you'll definately have to start doing more light work instead of all the heavy days.

Cheers,
Jeff