Imported MIDI file to song with tempo changes (not following changes)

If the person did not follow a tempo when they created the part then your hooped. I'm blown away at how many midi files are out there that are way off time. 
I think this happens with transfering from outboard midi gear, like akeyboard and they don'tsync the device to Sonar.. SO the keyboard sequencer is playing at 143 BPM but the DAW is set at 120BPM. 
 
Try this
 
OPEN the midi file for the part and take notice of the BPM And then see if it's following the grid.. bet ya it's off grid. 
 

Midi follows the tempo imbedded in the file which in turn sets the sequencers tempo.
If you OPEN that file Sonar will play at the imbedded tempo(s).  That's why you should always open a midi file you download. Otherwise a lot of important info is missing and the song will not play exactly as writen.
 
Importing a midi file ignores certain data like tempo and the sequencers tempo map will then drive the midi file following the tempo map. . 
 
That's why I say OPEN the file to see what tempo it originally used and if it's actually following that tempo. If it is not following that tempo you will need to manipulate the data. 
 
It will be unusable if it wanders all over the place. Even if off the grid, it needs to be the same tempo start to finish. see*
 
Someone might have played the part on a Yamaha midi violin controller in free time. 
 
Brainstorming this:
 
OPEN the file in Sonar. Insert a String VST, freeze the midi to create an audio track. 
Now you can change the projects tempo untill the tracks lines up with the grid, 
This works better with hard transients like drums, so you may need to record a drum midi track playing along and freeze that too. 
Zoom in on the leading edge of the first measure, drag the track(S) so the first beat in on the line. Now keep changing the tempo until the first beat of measure 2 lines up. This mightr involve mirco tempos like 123.456BPM
*This will only work if the track was played to a regular unchaning tempo. 
You get the tempo just right  and check the end of song to make sure it's still lined up from start to finish. 
Now drag the audio to a new midi track and Melodyn will convert it to midi again and it will now follow a proper tempo in any sequencer. Worth a shot. 
 
There are other things people do with time stretching and fit to improvation etc but I have no clue how that works. 
 
 
 

My findings with free download midi are 80% of them are dodgy.
I can often fix them buy quantizing and a bit of editing. But I'll find terrible timing issues and wrong notes all over the place. I go track by track in PVR and solo and look.
 
 For me if the drum part is good I don't really care to much about the rest. I just redo my own parts. Mostly I'm looking that the song is layed out and the arrangement is like the original so I can build from there. 
If anything there might be a good piano part because the author was a keyboard player.  Generally I end up deleting most of the parts because they certainly take away from the song and don't add anything anybody needs to listen to. Why is there always 3 bass tracks??? Big Bottom? Anyhow you made the best decision , I thought you were working with a killer track you just couldn't live without.