This is very strange,
My 86' non-turbo is suddenly having issues.

It feels as though the engine isnt getting enough gas. When around 4000rpm, without adjusting my foot on the pedal, it ceases to accelerate (or it is very "jerky"); i can instantly feel the loss in power.

I am suspecting something along the lines of either the fuel filter or possibly fuel pump. My brother is now sugesting a possible O2 sensor problem.
I plan on changing the fuel filter within the next days, but in the mean time - does anyone have any sugestions?

Thanks,

 

It sounds like your secondaries are not firing.

 

Don't listen to your brother. Check the secondary injectors, grounds and make sure your auxillary ports are working.

How many miles on the engine, have you ever had your injectors cleaned and how often do you take it to redline? Secondaries tend to plug first because they aren't in use as much as the primaries.

 

About 40k k/m on the rebuild - don't bring it to redline too often, (how often should i?)
and i've only owned the car for a few months- don't know when they've been cleaned last.

I'm still new to the rotary world..

 

The O2 sensor is not even monitored at WOT

 

ok man here you go i know exactly what your talking about i have an 86 fc as well and an 87 both have had the same problems you are describing, and by the sounds of it you being new to the rotary world and all be prepared to spend long hours with your car expecialy with you geting it used and with some miles on it , these are the problems and steps i had to take to get mine half way reliable, this list is in no particular order,
new injectors(4)
new plugs (4 ngk)
new wires
new fuel filter
new air filter
new fuel pump
new mass air flow syncer,
new throtal syncer
new fuel presure regulator
new oil presure regulator
new boost syncer
i have gone on to replace other things but they dont concern the issues your having right now, after you replace all those if you still have the same issues look on the side of your rotary on the passenger side you will see the air pump that says never remove well follow it back you will see a setup bolted to the side of your rotary that connects to that air pump , two syncers are hooked to it and plug in by your throtal syncer un plug both of those (not your throtal syncer) see if that helps any if it does that just means its time to replace that as well id tell you what its called but for the life of me the part name sliped my mind, let me know if this helps you out oh and one more thing buy a haynes manuel for your ne rx-7 its the bible for your car trust me it will come in handy, hope this helps.