Weird miss issue. Ever since i took my MSD ignition off my L98 ive been experiencing a weird miss issue. When you first start it up in the morning the car doesnt like idling at a constant 1,000 rpm on a cold start like it use to, it jumps between 1,100 to 900 until you put it in drive then its smooth.

When the engine gets hot though and idles down at 600 theres a miss and you can hear it because you can hear a tick everytime it misses, (think i have an exhaust leak somewhere) But cold or warm you can whomp on it and has plenty of power, its not struggling. I changed the fuel filter while it was doing this and there was no difference, injectors and all fuel related are new. Im leaning towards a sensor.

Then one day i was sitting at wendys drive thru a few days ago and after sitting in a big line it did it's miss a few times then the miss just goes away all of a sudden and idle is smooth for the entire time. Its weird because it stops when you sit in drive at idle for a few mins, but when you drive and come to a complete stop it will miss a few times. then stop. Plugs are good, acdelco cap and rotor and module and distributor are all new with just a few basic maintance i did to the car a year ago.

Im baffled and only thing i can come up with is possibly the TPS is off?

Any suggestions is greatly appreciated guys.