1990 Mirage

Well Hello, I Own A 90' Mirage... 2 weeks ago i started to notice that ive been losing alot of power in the engine, also when i go that the engine has really no power at all, my older brother took a look at it and thought it might of been the rocker arm shaft(exh) that we replaced about a month ago came lose again(maybe broke again) i checked that the other day and it was fine! i was wondering if anyone has any info on this before i start to take the engine apart and look for the problem with my father.
Could it possibly be the plug wires? maybe the plugs, the Dist Cap?
(The Parts ive replaced in the car are as listed
Tranny From 89 Mirage :Shifts Well No Problems With it:
Rocker Arm Shaft :Exh:
Alternator
Spark Plugs :Year Ago:
Air Filter :2 months ago:)

Also i did notice that the exht manifold is cracked in half could this also be apart of the problem? Any help on this issue would help:2cents:! Thanks

As you noted, the problem you are having is most likely ignition related. Make sure you used an OEM type plug such as NGK or Denso. Carefully inspect the cap, rotor, and wires. If you don't know how old they are, you may want to replace them on principle.
FWIW
YMMV

Thanks Alot... But A New Problem Has Started. The Car Has A Hard Time Turning Over The Starter Seems Fine But When Started It Makes A Winey Sound And Sounds Harsh, This Sometimes Causes The Car To Stall Out Or Not Even Start Itself

Soon After Your Reply I Noticed The Knocking Comming From Somewhere around the Drive Side Of The Engine, Just Fixed An Oil Leak Now Im having Problems Starting It... Any Help Would Be Nice

Following Fix Ups,
Fuel Filter :NEW:
Oil Sensor :New:

Drive Side as in driver's side or drive side as in side with the belts?

left side of engine(sitting behind the steering wheel) it knocks and makes a funny winey sound as its starting and its horrible to start sometimes wont i also found out that my dad replaced the ignition coil and all that also but idk what else to think! any help plz!!!!

"and its horrible to start sometimes wont"

Can you elaborate on this and be a bit more descriptive? It may be something as simple as a bad starter.

The Starting Is Ruff I Checked The Starter Its Fine But It Makes A Winey Noise As Soon As It Starts... I Just Got My Pluggs Changed And Its Running Hard They Said It Might Be The Injectors But I Think Sears Fucked Up My Car LOL... if you need more of a decp on the starting just ask...

When I Go WIth My Car Now It Seems Like Eather The TIming If Off OR...The Injectors Arent Putting In Enough Fuel. It Runs Like Crap And It Seems Like Its Skipping And Pops WHen It Runs