Re: Need different rod for streamers?
Re the 8-foot sinking leader you've been using:
I assume you mean one of the kind sold by Rio, Airflo, and S.A., with a plastic coating impregnated with lead or tungsten powder over a braided or mono core. These have their uses, but the problem with casting them when they're attached to the tapered tip end of a floating fly line is that too much casting energy is dissipated down the tapered floating tip, leaving too little to turn over the sinking "leader", which is more accurately described as a sink-tip. A splitshot-weighted leader (Frank Whiton's No. 2) can feel the same way, esp. if you try to use too much lead weight; and so can a heavily weighted streamer.
A better all-around solution is Frank's No. 4: a factory-made sink-tip line, probably rated as Extra Fast (Type 4 or more from S.A.; Type 6 from Cortland). Even these feel a little jerky in the turnover, compared with an all-floating or all-sinking line, but they work. You can find a lot of versions with 10', 12', or 15' sink tips. An integrated shooting head line like the Teeny (24-27' sinking head works well enough, though they're better for six-weight rods and above.
A digression for informational purposes: spey fishermen, of necessity, are experts at integrating separate sink tips (homemade sections of sinking line, sections of weighted-core line like T-13, or factory sink-tips as you're probably using) into floating belly spey lines as a system. Spey rods are very particular; they can cast a wide assortment of spey line types, but each line has to be properly chosen and configured in order to perform well on that rod. Most spey line systems have most or all of the front tapered tip cut back to a larger diameter and a loop added, to which various sinking heads, tips, or floating tips are connected loop-to-loop. A rough rule of thumb is that the sink tip should be two AFTMA sizes lighter than the floating belly. For single-hand rods, you can buy multi-tip lines that are designed the same.
A new integrated sink-tip line is the cheap fix for your rod. But one way or the other, you have to throw some serious weight to comfortably fish heavy flies near stream bottom, and that's asking a lot of a five-weight rod. It may be time to consider a heavier system. A seven-weight rod and line will do it easily and comfortably; it's not too heavy for trout, and it's good for bass, redfish, etc. Most fly anglers add other systems when the limits of their first one is reached (and of course, a five is a great all-around trout system). Moving up or down two weights is a logical approach - although in time, you may fill all the niches. I have outfits from 3 to 12.