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So I’ve had my 66 M20E for all of a month now and I’ve been having a problem for the last 2 weeks. When I’m at low rpm and add throttle (just a little or alot) the engine falls off (sputters and chokes) for a second then runs better once I get up to higher RPM. I’ve repeated this “condition” at all mixtures. Full rich and all the way back to full lean. Leaning the mixture makes the problem worse. It seems to make full power during take off and curse seems fine. Some info: -IO-360 A1A, 950 SMOH. 300 since top overhaul. (to help oil consumption) -At idle, the plane is fairly smooth but feels like it half-misses every 4-5 seconds. I’m told that's not uncommon. -Fuel pressure is normal and centered in the green. -Oil pressure/oil temps all in the green. -Electric fuel pump on/off makes no difference. -Mag check during run up shows 30-50 prm drop for each mag. -in-flight mag checks were fine -if I slowly pull the mixture all the way out I get a 30 RPM rise before shutdown. -Left/right fuel tank makes no difference. -The battery is 8 years old and getting weak but still does its job. -Left mag; 500 hours since it was overhauled P/N 10-163005-2 -Right mag; 500 hours since new P/N BL600644-1 was installed -EGT’s seem to be normal. 1200 to 1350 on average during cruise -I have a small oil leak which I think is coming from the prop governor. It makes a mess but RPM control is stable. It needs to be adjusted as it gets to 2750-2790 rpm. I just take off with half a twist out and it’s stable at 2700. And I’m sorry but I don't have an engine monitor yet. Only EGT’s. I’ll install a monitor during the next annual. I’ve only had the plane a month! I was being supervised by a mechanic today and we pulled all the spark plugs. All tops were good, bottoms were ok but just a little wet. We cleaned and gaped the plugs. Reinstalled and no improvement. Then we removed the injectors and soaked them in acetone for an hour. Reinstalled with no improvement… He recommends that we replace the left mag with a Surefly and overhaul the right mag to see if that helps. The mags need to be done but I feel like he’s not confident. I’ll be going back to the plane tomorrow. What do you all suggest I check?

Best brand/part # for fine wire plugs for a 1967 M20F with IO360 A1A with a RayJay..