app to monitor apps

I have an iPhone 4s i had approx 25 apps "some free some paid" on Wednesday my phone battery started dropping fast from 95% (at 7:00am) to 30% (at 4:00pm) and I'd only sent 2-3 texts .. It was full charged again by 7:00ish and before midnight it was back down to 65% so I plugged it into the comp and removed all the apps ... It's been fine since , after 1 1/2 days it is still at 73% .. I want to re-install the apps but was wondering if there was an app "i'd prefer a free one" that would monitor which app/s are running and how much power is being used...

There are a few out there. You need to find one specific to your requirement, and that means find one that displays which apps are using what. You clearly had something on there that ate a lot of power in usage.

I tried typing a few different things into the search at the apple app store but no luck , i'm not sure what to call it ...
When i noticed the battery going down on Wednesday I only had used the phone to text a few times , i did have garmin on for a few minutes , and checked the weather , maybe 1-2 more apps on and off .. I even re-booted the phone but whenever was running must have came back on because the battery kept dropping ..

Search the app store for SYS activity manager. It costs 69p and is pretty comprehensive. They have a lite version you can try before you buy...