Recently when I would start up the RX-7 (1984 GSL-SE) the idle would be great, around 2,000 but when it is fully warmed up it would jump down a little, then head straight to 0 and turn off. Any ideas what can be the problem? Because it's a modified RX7, well only the exhaust, it has a mind train 83 exhaust on an 84' I guess the Throttle Positioning Sensor may be off... what other thoughts comes into mind with this? Thank you for all the comments in advance.