e34 530 coils

Picked up a 530 w/115K. Has a shudder/loss of power on load.
First the plugs which no one carries around here in central CA. Kragen will order the f7 for 10.99 each.. Yeah right.
Also looking at coils and here's where I dunno. most are proper 12 13 1 703 359 but first two up front on pass are 3360 not 3359. I cannot even find the part on OEM.com or anywhere to see what application it's for. Plugs look similar to others w/correct coil. Could these two coils be the culprit for shudder loss of pwr on load? and does anyone know what car they might go on?
Anyone
TIA

I have a 95 530ia. The oem coils are Bosch 12 13 1 703 359. As for the spark plugs they are Bosch F7LDCR. I ordered my last set at www.autohausaz.com for $2.51 each with free shipping for orders over $50 and no sales tax since they're in Arizona, came within a week. I'm in NorCal.

It sounds like one or more spark plugs are misfiring. Check the condition of the spark plug boots. Make sure they're in good condition with no cracks, otherwise they'll short out causing the plugs to misfire.

Bavarian Autosport shows the 3359 as the correct coil. They do not recognize the 3360 in their database. They also have the F7 plugs for 4.95 each. Call you local BMW parts department and run the coil part number through them and see what it goes to. It does sound like an ignition problem. I would not drive your 530 until you get a handle on the issue as you could do serious damage to your catalytic converter. Are you getting a check engine light? Do you know how to check for trouble codes? How do the spark plugs look from those two cylinders compared to the others?

I forgot to add, I use Bosch Platinum 2's in my 525. Bosch is doing a rebate on spark plugs. The P2's have a $1 per plug rebate.

No check engine light. That's what troubles me.
If I had a misfiring cylinder the light usually would go on.
Plugs from the odd ign. coils look similar to all others.
I am going to get a set of plugs (F7)and one new coil (#3359) and do all plugs first and if that doesn't make a change I'll go thru each coil one at a time and replace with new coil. If I'm back that'll mean it was neither coil or plugs

THANKS

Chased the shudder/loss of power for over a year and a half. Go back to your coils, pull one out, take a spark plug and stick it in the end of the coil boot. If you touch the spring, change the coil boots. The spark plug should fit snuggly in the boot. It should POP out when you pull it out. I just replaced all the boots, and the problem has been resolved. Hope this helps.