poor running, help needed please!

[Reno]

i have a nissan micra k11 1 litre, im having a problem with the running of the engine, when its cold, it feels like it has no power at all, when the car is warm there is a definate improvement but still hesitates at higher rpm and feels no where near as fast as it used to, ive tries resoldering the throttle body and it hasnt made a difference, ive also checked all the sensors on the throttle body with a multimeter and all he reading just about match up to the haynes manual, does anyone know what else it might be?
sorry about the long question, just trying to be detailed, any help will be greatly appreciated

Simon

 

[superls]

have you serviced it lately? bad plugs distributer and oil/blocked filters will give problems similar to yours

 

[Reno]

have you serviced it lately? bad plugs distributer and oil/blocked filters will give problems similar to yours

yer i serviced it a few weeks ago, i didnt change the spark plugs tho as i bought some iridium ones not long ago, do you think it could be the gap on the spark plugs? and i didnt check the distributer i'll have a look at it and see if i can find anything

 

[Reno]

i have now changed the dizzy cap and rotor arm, its made a little difference but still seems to lack abit of power at high rpm, ive had a little read through some other posts n i think it could maybe be the lambda sensor?