You could cause excessive wear on the cylinders with the misfire. How excessive will depend on who you speak with… (Burned valves – Warped heads so on)
The most common thing you will hear – The exhaust catalyst will be damaged by the unburned fuel being poured into it. Best case, the converter breaks apart, worst case it clogs. Both cases require replacement at $500-1000.
Chances are if your plenum gasket has failed there are other gaskets (Vacuum line) That need to be addressed.
Your issue sounds like a lean fuel condition or a fuel atomization issue…
Things to check.
Fuel pressure.
Fuel filter.
Fuel Pressure Regulator.
Tps. (throttle position sensor)
Timing.(Vacuum advance)
Basic tune up.
How many miles?Time for a overhaul???
Check Codes- Pre 96 OBD1 You will need to preform (KOER-KOEO){KEY ON ENGINE RUNNING}{KEY ON ENGINE OFF}TEST.
After 96 OBD2 You take have codes checked at autozone.
There are even some items on the transmission of some cars and trucks that can cause issues like this…
Could the engine be throwing its self into limp mode???
This really sounds like a lack of fuel or fuel being cut off.
Are you getting any smoke out of the tail pipe???Black = To much fuel.
Im sorry I missed you original post on this issue…
Can you give me any more info… MAKE – MODEL – YEAR – ENGINE -MILES.