Guys, I have a small block Chevy 350 stroked to 383. It ran smooth without any problems for about 25,000 kms. about 6 weeks I noticed it was running rough and was down on power. It happened gradually, it wasn't overnight. Checked plugs. One looked bad (#8) with a buildup of deposits. Changed all the plugs. Problem was still there. Checked the plugs again and #8 Looked new. Checked plug cable and it was no good. Changed the rotor/cap/cables and set timing and tps. Power is back but I still get a vibration.
Engine will idle smooth from 600 - 900 then vibrated at about 1000, smooth from 1100 to 1400 then vibrate from 1500 - 1600 then smooth to 1900 and start to vibrate again from there. This stays the same whether in neutral, drive, accelerating/decelerating or under heavy load pulling a trailer.
Any ideas/suggestion as to what the problem and solution maybe?
Thanks,
Mike