1995 SSE idle feels funny...

I have noticed that when the pressure gauge gets to around 220 my car starts to shake ever so slightly giving the impression that it will cutoff at any time. Would a bad sensor (out of tthe 20 or so in this car) cause this to happen or could it be something simple like a bad spark plug? I'm hoping someone will respond with something I can work with because changing sensors on this car seem to be expensive. Any help would be appreciated and TIA.

yes I am, sorry about that

yes I am, sorry about that

I wouldnt worry about it. My Bonneville did the same thing when it got hot. Almost like as if it was running like a diesel engine. Also, I would caution againsts letting your engine get that hot. Here is a link showing why...

Ok first off 92 models didnt have a plastic intake and there is a big diff between Series I and II engines. Running a 180 deg thermostat isnt only going to give you bad gas mileage but its also just a bandaid. Fix the problem not the symtoms of the problem. I doubt pontiac would have been putting 180 deg tstats on in 99 because the epa wouldnt let something like that fly. I dont know what the storie is on adding a trans cooler. There is more than often already one mounted in the radiator from the factory.

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Thanks, if it is anything else I'll let you know