ive got a 90 jeep with 143k, i already know i need to replacethe exhuast manifold, but it developed a miss under light throttle, seems to just hicup once,feels like a jolt, than clears up..seems to be running a little rough too..thought it was bad gas and threw in some seafoam in the tank, bu that didnt help..right now it just seems annoying, but i dont want to be stranded on the interstate tommorow...could it be a failing cps? starts right up, oil pressure is normal according to search...any help is appreciated in advance..