Try re-gapping your spark plugs to around .28-.30. That might fix your problem with the rpm cutoff.
Sounds like you have a coolant leak, or a bad head gasket. That might explain the white smoke.
Does your car ever overheat past the middle section of the temp guage after running for awhile? You might want to flush the cooling system and put some new shit in. 50/50 coolant and water.