The other day I changed my sparkplugs with no problem (Autolite 985 gapped to .35) as soon as i started it up i had an obvious misfire. I then replaced the wires and still had a miss. Pulled one plug that i suspected because i had trouble putting it in and the gap was messed up so i fixed that. Now it only misses at start up but when im at a stoplight it will die on my everytime unless i put it in park or keep my RPMs up. What could it be?