i have a 1988 rx7 non turbo sometimes my starter works and sometimes it doesnt its real speratic i made sure all the wires are tight and corrosion free any ideas where to start looking or common problems

 

The solenoid is either dirty or sticky. You can rebuild it, or just get one at the auto parts store. The parts store starter will likely have a warranty.

Oh, occasionally it is the ignition switch itself. If the starter always works when you wiggle the switch, then the problem is the switch.

 

If it's manual transmission, there is an interlock switch on the clutch...starter will not operate if the clutch is not depressed. When those contacts are dirty, the starter solenoid does not get grounded. If you can get it to start by pumping the clutch, I'd suspect that (similar to Aaron's thought about wiggling / cycling the ignition switch).

If it's the clutch interlock switch, it can be cleaned, replaced or by-passed. Note, this is the switch activated at the bottom of the clutch stroke. There is also (if cruise control) a switch near the top of the clutch stroke to disengage the cruise when the clutch is pressed.