My car was running excellent, but now it is dieseling on acceleration after I performed a minor routine check-up on my '85 244 DL. The engine also has a new sound- the best I can describe it as more "bass" coming out of the muffler while accelerating. Let me tell you what I did:

Changed spark plugs (Bosch WRS7C)

Changed distributor cap + rotor, aftermarket

Changed spark plug wires

Pulled top vacuum hoses + flame trap hoses to check for cracks and put back on, had to
trim the Oil Trap to Valve Cover hose (picture: http://www.fcpgroton.com/images/1317667.jpg) because it had cracks on the end. Ordered new one, not sure if old one is leaking now as it is just barely attached at its connection. I checked this by pulling it completely off while idling and the idle rpm drops. I put it back on and the rpm goes back up.

Replaced top vacuum hose (about 2" long) that goes from intake manifold to a valve (half white & half black, about 2" long), then goes to the vents (I believe). On very top. Replaced with an aftermarket of equal size.

Checked valve lash and replaced valve cover with new gasket. Valve lash good.

BTW, I have a leaking vacuum part in the vent system. When I accelerate I can hear it hiss, and when I shut the car off it hisses, then the vent closes.

BTW, I thought that maybe my plug gap was to small at .026 and I changed it to .030, but it didn't affect the problem.

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I believe the source of my problem is vacuum related. I'd like to hear what other people think. If you think it is vacuum related, where can I get the parts? Also cabin vent vacuum parts? The only one I can find is the flame trap hose at fcpgroton. I think that vacuum hoses that are 18 years old quit sealing once you touch them.

Thanks for you ideas,
Joe