wteebo

Ok I have surfed numerous forums trying to find an answer to my mysterious noise and it seems that there are a lot of possibilities so I thought I would post my situation with every detail I can to maybe narrow the problem, so here goes:

I have a 1991 Accord EX with the A4 motor, about three weeks ago I did a tune-up - plugs, cap, rotor, and also cleaned the throttle body. Here's what I am getting now, not sure if these are relate, on acceleration at any speed I hear a "fluttering" sound, or a metal rattle sound - it sounds a lot like a diesel motor sound but not nearly as loud. It's as if the throttle body door was extremely loose and it was fluttering. Thats' the best way I can describe it. It doesn't do it when cold. I can't duplicate the noise in the driveway putting it in drive and accelerating (holding the brake). I have checked the obvious: plug tightness, wires, or anything that may be loose. My fluids are where they should be (oil, coolant, tranny). There is no power loss on acceleration. It's idles fine except for a subtle hiccup every so often when sitting at a stop light (the reason I did the tune-up). I have checked for exhaust leaks but I can't replicate it when I am out of the car so I haven't gone very far with that theory.

Any and all suggestions would be appreciated!