Hello Rx7Club,
Now I've pondered for days on whether i should sit down and create a new post on this issue or not but after many hours searching and talking to folks it was decided that is is prolly for the best. Please everyone stop me if this has been discovered before.

a couple of months ago i purchsed a 90 GXL that had been sitting for almost two years. Changed the Battery and it started right up. Only noticable problems after that was leaky cat and bad tires. Drove it home, no problems..runs smooth(relatetively speaking). a week later i noticed the RPMs taking a hit whenever i used power, engine would slow down for a sec then climb back up, no more than 100 rpm. Voltage from Alt never above 13V.i decided to change the alt. a couple days later, the water pump starts leaking. while changing the WP i replace the Plugs. I finnally fire it up after days of sitting and i have a new problem...

its idles a very little rougher than it did days before, stays around 700 rpm. but when i step on the gas pedal and i notice it runs really rough and if i just hold the pedal at any point it will cycle from rough to smooth and back again repeatably forever. when it smooths out its really smooth, like the way it should be from factory then gradualy roughen up and gradualy back to smooth again. its timing is perfect, maybe 4-5 secs to make ome revolution from smooth to rough and back.

things i have replaced.

spark plugs
plug wires
alt
battery
water pump
belts
oxygen sensor

Now my next course of action from to clean the ECU grounds and valcum leaks. I have checked already for any loose cables or connectors. Is there anything at all that i am missing that i should check. Is there any obvious problem i am overlooking. This problem has hummbled me once again. Thanks for anything helpful at this point.

 

If there was fuel left in the tank, it has probably turned to lacquer. This could be one problem

 

It has had 4 or so full tank refills since i got it. Adding Fuel filter to list.

 

Could this be a grounding issue??

 

try replacing your coolant temp sensor on the back of the thermostat housing. this caused problems with my cars' runnability.

 

weird thing today. i drove the car on the highway and it seems the problrm is intermitted as it wasnt doing the vibrate thing at all. so im seriously thinking whatever it is, it is electrical. either a bad ground or bad sensor. i will ad coolant temp to the list and probly make it top prioirty as i didnt have the problem until i did the water pump. Thanks for the replys

 

Okay nevermind. the problem still exist!!! on the drive back home from work i noticed it come back when the engine was still cold but once the motor warmed up the roughness mostly wentaway but came back only beyond 6K and even then it wasent steady. very intermiittant. This is really really making me believe its a electrical or sensor problem now. i Purchased some Techron fuel cleaner just for ***** due to the fact the car did sit for two years.