your speedometer twitches.. is it a really high pitched noise.. like something grinding??? LOL cuz I have that too! it's the cable for sure.
talk about rpm changes... my car stays at 2000 if its really cold.. then around 1500 if it's a little warmer.. today it's like 0 outside.. so it's been at 1000 all the time.. I think it's the computer adjusting the idle according to how hot/cold the car is.. probably because of a stuck thermostat.. which I already know I need.

which is why I made the cold air deflectors.. too lazy to get the thermostat changed.. (too cold anyways).
Hey white_sr5, I've already spent more than $2000 fixing my car, and it's not even finished yet, mine is in pretty good condition, and only last summer I started getting rust.. it had NONE when I bought the car in january of last year. So far about $900 for fixing/upgrading suspension (I chose to upgrade springs to lowered springs anyways.. otherwise it would be about $500 for the KYB struts installed) about $420 for a new rad and oil cooler lines, about $350 for tires, $120 for cap, rotor and wires and many other miscellaneous things.
Next on my list are: getting the clutch kit installed, which I already bought OEM at about $200 (got a nice discount on it), Thermostat replacement, Fuel filter replacement (which might cost a bit, depending on whether or not I have to replace the fuel line too, since the last owner didnt replace the fuel filter when he was supposed to). Also getting the car repainted is on the list.. which is not really necessary if you don't care what your car looks like, but I don't want my car rusting away.
You're not alone man.. my car runs ok, but I know I'm in for it if I want my car to run and look like 1owner's car.. A1 condition!

(you gotta see his car!

)