Need some help

[JHAAz]

Whats up guys

Here's what we are working with- 87 LXI A20A3 w/ EFI & 160K miles

my problem is a stumbling idle upon initial start-up. RPM's raise to a good speed (1200-1500) but then after a few seconds it will start to stumble and drop to 200-300 then catch itself and raise back to 900-1000, then repeat until it starts to warm up. Ive read several "rough idle", "cold start issue" etc. type threads and can't seem to find solid enough info to diagnose my issue effectively. My hunch is the IACV, but I dont want to remove it if I dont need to as to not waste a perfectly good gasket seal. I also thought of adjusting the idle screw on the TB but seems like a MOFO to get to. I have cleaned the TB with carb clean several times and know it is not the issue. cap and rotor are brand new and plugs are good.

any suggestions?

[nswst8]

Does your throttle body have a fast idle control (close to throttle body air intake opening and firewall) You can remove the 2 top screws put your finger in to sense for suction at intial start up. No suction should be present when engine warmed up rad fans comes on.

Don't confuse this with the IACV between the valve cover and throttle body.