86' 250sx idling issues

[SCRAMCHARGER318]

howdy i got a 1986 250sx all stock except for a cobra exhuast, but everyother time i ride it, it wont idle it just keeps running lower and lower until it dies. but then the next time i ride it she will idle fine i have rebuilt my carb 2 times thinking it was a clogged pilot jet or improperly installed pilot screw o-ring but that is not the issue, also i have checked all connections and grounds and they are all tight and free of corrosion. now im thinking it might be the cdi box but i dont know what they can do when they go bad. or possibly something else in the electrical system, but im looking for ideas any would be appreciated.
thanks

[Dirtcrasher]

The SX is known to break wires at the CDI, unwrap the tape and check it out; I was a full user of suspension and mine broke off.

This is how I treated her



Otherwise I would suspect gas cap venting or some crap in the petcock screens (1-tube, 1-screen) stopping the gas flow.

When it does it, shut off the petcock and loosen the drain screw. Is there gas?? If not, you have a flow problem.

Otherwise I would look to electrical............. Piece of cake............