Jeff: Now that you have installed those snazzy platinum 4 plugs for 26.00+ plus tax, get ready to throw them away, or try to get your money back claiming the parts guy sold you the wrong plug for your car. Ive also heard they break up and fall into the engine. You most probably have a resistor type plug installed now, and thats very very bad. Go see if there is an R in the plug model description, the "R" means resistor. You probably already have resistor caps on your HT wires (metal caps) and now your running two resistors on each plug. Get the correct plug requirement for your engine from your owners manual, gap them at .032 exactly, lightly grease the threads when putting them back and torque them in. I would also order a new Ignition coil from www.*************** (Look at your original coil and Make sure what side bracket you have.) These tiny Bosch coils only last around 10 years at the most. If it has a sheet metal stamped centersection, chuck it....
If your spark color is orangy red, not whitish blue, thats the answer. Good spark is white hot and you can hear it snappin. Dead givaway: Your new plugs helped for a while, but because your spark is weak, they are getting contaminated with unburnt hydrocarbons, Ill guess on closer examination, they will have these little whitish tan spots on them now that looks like sand. So the plug is getting fouled, and because coils die slowly, the last two weeks that have passed by caused the coil to deteriorate even more.
If after the right plugs and coil change doesnt help, write back...
dave.....
If your battery is older than 4 years, chuck that too, and clean up the battery terms bright and shinny before you install the new battery

"93" MB 300TE 4matic 187,000 miles
"85" Volvo 740 Turbo Wagon
"85" Honda Limited Edition GoldWing