I'm working on my nephews car and It has stumble when taking off, seems to surge slightly while holding a constant speed & I noticed last night when it's trottled up in park it spark knocks bad. Any suggestions? The car has 64k and I believe it's had plugs and wire done earlier this year and he said it ran good after that, but then it started running worse again.

Trevor

 

My car was doing that a while bad. I replaced the plugs/wires/opti. I dont know for sure which one solved the problem but one of them did it for me. I got the surging and the stumbling but no spark knock.

 

Im not positive what spark knock is... are you talking about arching? But if its stumbling on throttleing it, an easy way to check to see if maybe its a single plug/wire is to disconnect one at a time and see if it changes the tone of the car or not. If it doesnt change the tone, then you found your culprit, if it does, then go on to your next one. If it doesnt change the tone on one of the cylinders, it could also be a clogged injector, as I had that happen to me last winter and it kinda did the same thing as youre talking about on steady speeds.
Also might want to look into a fuel filter and o2 sensors, oh and of course the optispark. Have it scanned for possible codes that were thrown. Start off with the basics, if its running decently, its probably not something too terrible.