nissan micra misfiring k11

i havea 1998 s reg 1l micra and have a problem with it misfiring and running on 3 cylinders every so often.i have taken it to 2 garages now who dont seem to know what the problem is. they have dne a test on it and it keeps n coming up with error code 55 which as you already prob know means theres nothing wrong with it. i first had a problem with the distributer so changed that with a working second hand one coz it wouldnt start. i changed the dizzy cap,rotor arm,spark plugs,ht leads an after a bit of trying to get the car to start it did. but then this problem occured. my friend who has a garage said its possibly the throttle housing so i again changed that but it was still having the problem. i have put wells petrol treatment through incase it was the injectors but nothing is working.i have just been to my friends garage and whe he disconnects the plug going to the throttle housing the engine doesnt chug or misfire but i cant use the car with this unplugged.when u are driving and this chugging happens the engine check ligt flickers and there is a clicking noise coming from the right hand side of steering wheel above the fuse board.. this is really confusing coz nobody knows whats up and i cant afford to keep replacing parts when its not them thats the problem.. please can somebody help with an idea of the problem coz i dont want to get rid of the car due to it being a good little run around before this happened.. thanks n hope to hear from somebody

My car was intermittently running on 3 cylinders. usually once it warmed up.

after checking all of the usual things mentioned on here, AFM/TB plugs leads, etc.

it turned out to be an injector sticking OPEN. i changed them over with a spare rail .

my problem solved...

the injectors are not very hard to remove yourself. might be worth getting them tested / cleaned.

If it is intermittent, it could be the distributor had one go on me once, took ages to find out what it was and I took it to heaps of different mechanics. If it runs fine for a while then after a while starts to misfire it maybe the distributor as it gets hot it will foul and once cool it will run fine till it heats up again. So could be that if the symptoms sound the same.

it seems to be worse when i have just started it up and the engine is cold. i i have ran this high grade petrol treatment through for it to unblock any injector problems.

my mechainic reckons it could either be the timing chain? or the ecu bot both expensive jobs and if i do one it could be the other if u get what i mean.

My injectors had a mechanical issue, no fuel treatment will fix that.

if you can find an ECU at the breakers, or in a friends K11, its a 10 min swap at the worst.

then you will know if its ECU. I doubt very much its the timing chain.

i have sneaky suspicion it could be the distributer i put on it. at first it wouldnt start so i put a second hand on on it and it started but im not sure if its working properly coz i found a forum on the net where smeone had exactly the same problems and tried everyting but solved it when they changed the distributer? the timing chain is noisey but ive had one go on an older micra but it as nothing like this.i have reason to believe i cant just swap the ecu to see if it is tht coz of something to do with the immobiliser wont let me use my key? is this right?and does it have something to do wth the ecu? THANKS

on the pre-facelift 98 the ecu nats immobiliser is tied into the keychip, transponder and nats box behind the heater adcol
if its a facelift 98, then the transponder is different (7 or 8 wires instead of 4 iirc)