I have a 1984 240 DL wagon. For the past few weeks the car starts up quickly enough but then as it warms up it stumbles and idles unevenly. It will stall if put into reverse. This uneven warm-up lasts for about 4 minutes and then everything runs smoothly and acceleration is fine.
We took the wagon to our local dealer where they kept it for about a week. Their mechanic was able to duplicate the problem but had no cure. The spark plugs were replaced because they were fouled and dealer told us to give the engine more high speed turnpike running. Well, for a week or two there were no incidents but now the same problem has reappeared!
I originally thought there was a fault with the automatic choke or perhaps a failure in the cold start injector. The dealer said they checked everything out and could find no problems. What I did not like was a remark from one of the service managers who said it was too bad there was no diagnostic computer onboard they could plug into and also they had no mechanic who had worked on the "old" Volvos.
I am hoping someone out there has some idea what could be causing these warm-up problems.
TIA
jon