1989 screamer

[fixkick]

Also the plenum heater black plate two wires can i delete that? To prevent the extra gaskets required and simplify the design? My 89 5 speeds seem to not need it and i warm my truck up 5 minutes prior to running no smog requirements so i dont see the harm i know its for atomization etc but the fuel savings vs a vac leak ill pay to play haha. Thanks boss

ok this is  a 5speed stick box. (told now)
not 3speed
so make real sure the  3speed intake manifold has no VACUUM MODULATOR port , there and if is there is not leaking air. it for sure is not used this port on any 5speed. nor 4speed A/T
the heater is only for the 3speed,
so is useless.
yes get rid of that and only use the 5speed gaskets.

you have this huge leak some where, intake plenum induction leak is the brake booster tested for no leaks?  (I use cork on the hose leanding to it) to prove that. so easy

btw the fast idle pins are A13 not at zero volts, ground is fast idle for steering overloaded (PS)
A2 pin is fast idle to from DIODE "OR" logic gate device,  A/C on,  headlamps on, Blower on, or rear defrost heater option on.   must be

page 9 here shows idle up pin A2 and A3... A2 is A/C active, and A3 idle up all others.
a2 =12vdc = idle up command
A3= 12vdc = idle up.  
https://fixkick.com/ECU/89/1990-scan-ECU/allpages.pdf

I will assume all things related on this  32 year old car,  all idle up's bad,  and air leaks, and TPS idle switch failing making ISC dead. and ISC and IAC leaking air.
i check them all, and be sure they are not wrong,  the air leaks all added up; add up more RPM.!
but once all air leaks are gone the engine stalls and needs right foot pressed a bit to start car, hot. cold the IAC adds lots of air below 150F


pin a14, must be zero volts at idle,  or the TPS is bad or never calibrated,  (5v here means ISC is offline, means unregulated RPM but not screaming)
below is crude lacking most pins.


vacuum leaks are not easy
as the master said, Archimedes, (before space craft) nature (on earth) abhors a vacuum. ( nature and time and aging love to  find a way to fill the vacuum with 14.7PSI sea level air.)

that in turn means  the gaskets crack and air sucks in like mad. (entropy) yours had 32 years to fail. not small that.