2003 pt cruiser gt

i have a high pitched whistle coming from my car at all times when my car is running but when im driving above 2500 rpm’s it goes away as long as the peddle is steady down but when you let off it screams again also my check engine light is on and it blinks when im sitting in idle and the engine rocks so the whole car runs ruff i have changed the spark plugs and wires what possibly could be causing this high pitched sound

A blinking "Check Engine: light indicates a severe problem with damage to the emissions system likely to occur soon (if it hasn’t happened yet). Do NOT drive the car in this condition!

The high-pitched whistle could be a vacuum leak. Is it possible you knocked something loose when you were changing the plugs and wires?

we did the plugs and wires way before this happened but i do agree on the emissions i had it scanned and it said evap canister leak and i have got codes for purged fuel system or something of that i still owe 9000 on the car is this problem severe enough to get rid of it cause i am a single mother and have no money to fix this major problem and have no idea what could be wrong

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

Regarding warning lights:

  1. if the coolant temp light comes on, shut off the engine ASAP

  2. if the oil warning light comes on, shut off the engine ASAP

  3. if a FLASHING MIL/CEL comes on, shut off the engine ASAP

    ASAP means driving to the berm of the highway right now and not waiting for the next exit.

But if the MIL/CEL is not flashing, then it’s not an urgent indicator.

It does sound like there may be a vacuum, or air, leak into the engine intake. Such a leak would unbalance the engine idle (cause it to run rough).
The charcoal canister is part of the EVAP system. It is connected to the engine intake by a hose, or two. This hose (or, two) may be defective; or, the control valve may be defective. There are other hoses, and control valves, between the engine intake and the gas tank which are part of the EVAP System.
It can be difficult to find a shop which can troubleshoot and repair an EVAP System. Ask around. A mechanic should be able to trace the high-pitched sound to its source. An older mechanic may not hear frequencies that high (FYI).