I'm having a problem with my lifts. I lift a pretty generic split:
Monday: Chest & Tris
Tuesday: Cardio
Wednesday: Legs & Shoulders
Thursday: Cardio
Friday: Back & Bis
Sat & Sunday: Rest OR 1 day of cardio

I lift 3 exercises per muscle group. Problem is for instance chest - tri day. A typical day looks like:
Dips - 3 sets
DB Flat Bench - 2 sets
DB Tri Extensions - 2 sets
Flat DB Flyes - 2 sets
Skullcrusers/close grips - 2 sets
Incline DB Bench - 2 sets
Cable Push Downs - 2 sets - the last is a drop set

I work every set to failure. By the time I'm at Inclines - I'm freakin wiped. I can't do anything near my personal best. If I switch the flat an incline bench the next week - my weights are totally different. Long story short... I can't lift as good at the end of my workout. Should I be worried about this? Another thing to note is that my reps/weights move up every week - usually 2 reps per exercise a week. Does that sound reasonable?

More food, more rest - I don't think either of those are a problem... I'd appreciate any comments.
Thanks,
Tim