i have a 93 coupe with a b16 and a p72 computer, vtec works but only sometimes, when the engine is at operating temp or when i get on it driving the car goes into safe mode and vtec doesn't work, i cleaned the solenoid one day and then it worked no problem, but it goes in and out of vtec and the car starts jerking, i'm at a loss with what it could be, does anyone have a clue?????????????