i have an 85 12a rx7 with a stock nikki carb somewhat freshly rebuilt with racing beat exhaust and have not removed the air pump.

My issue is when i am decelerating and the engine gets toward idle, it hovers at about 1100 rpm for a couple seconds before returning back to idle. Sometimes, if i drive on the freeway for about 10 or 15 minutes, it will sit at the 1100 rpm mark for a good 10 seconds or so before finally going down. I know my shutter valve is working properly due to having a new one on there and having tested it for functionality.

The other issue it has is if it doesn't hover around 1100 rpm, it will go below idle for maybe a half second and then go back to idling normally. It is just long enough to sound like it is going to die. this has been happening since the carb rebuild.

My question is does anyone have any idea what may be causing this? maybe i messed up somewhere in the rebuild? maybe it isn't even carb related and i plugged a hose up wrong? i did replace all of the rubber while the carb was off.

 

This may be a silly solution, but could you have overtightened the dash pot? Are tou sure that throttle and choke cables are adjusted properly?