Volvo Repair: black smoke, flaky idle, poor performance, rotten egg smell, car fires

Question
95 850Turbo 170K: couple of months ago, I scraped intercooler on curb and screwed it up.  Immediately upon next crank-up, black smoke from exhaust, flaky idle, poor acceleration, had to nurture gas pedal to keep car running at times. (CEL diagnostics indicated cylndrs 4 & 5 were misfiring and catconv damage.  Not knowing intercooler was the problem, i smelled rotten eggs and saw black smoke and thought it was catconv...installed magnaflow, no resolution but no rotten egg smell....checked MAF...not the problem.) Car would NOT stay running in Park or Neurtral, but usually would in Drive or Reverse. Due to finances had to drive  this way for couple of months..UPDATE last night put in used intercooler and new Nissens radiator.  Black smoke is gone. Runs fine when cranked and driving. Accelerates quite nicely...although there is a noticeable lag when pressing the accelerator. Now the cooling fan wants to stay on and run down battery. Also, cold start, car fires up but won't stay cranked until about the 4-5th attempt and I have to nurture gas pedal.  If I turn off car I cannot get it started again until approximately 1-20 minutes of sitting and it will start but is tenative about. Also, when it does start the baseline idel appears to be about 100 RPM's lower (about 800 RPM v. 900 RPM) than before all of this started. Whatever mechanism /device that monitors idle upon start-up will kick the idle up to about 2000 RPM and it can hang there longer than previously.  Also, upon start-up if it doesn't get that high it kicks down much sooner than it previously did.  Please advise.

thank you!!!

Answer
Gibby, Check to see if your turbo hoses have any holes in it. If you run the car you may be able to hear air being sucked in.  Replace the cooling fan relay for your fan.  I still think that you should recheck the MAF by unplugging it, let the car surge, then replug it in.  If the car dies, replace it.  Roger