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I am driving a 1993 Buik Regal.  Frequently the engine will begin to rev without me putting any pressure on the gas, or even on the flip side, when I am trying to speed up the engine will not rev and the RPG's do not increase, the car has even stalled a few times while driving.
One person said it may be an issue with the "mixture"?  Any thoughts or ideas would be greatly appreciated!  

its time for a some professional with a scan tool to take a look at the system....

is the check engine light on????? if so there will be codes...

but i would start before doing anything else with a cleaning the ground wires....    as soon as i got any codes out of the computer... and wrote them down...

take the battery terminal off the battery... pull the bolts out... look inside at the ring terminal inside...  if you see corrosion.. you can either try to pull the rubber boot off the end of the cable... or usually pour hot water over the cable end and fold the rubber over to expose the brass terminal...   a stainless steel tooth brush from the hardware store works best.. with just hot water to wash it all off...

if you can reach it... the other end of the battery negative cable attaches to the back of the motor ... 15mm or 18mm tools are required to remove it.. and the mounting stud from the engine... clean the ends of that cable also...

bad or corroded grounds cause all kinds of problems...

there is also a ground connection somewhere on the motor for the computer .. on that model i don't know where they attach it... it needs to be cleaned and verified... it is usually near the thermostat housing... but it could be almost anywhere..

the reason for cleaning the grounds.. if they get intermittent... the computer gets it grounds from the motor... when they get dirty... the computer can get weird voltages and it will cause it to do strange things...


things to look at when the scan tool is plugged in...

coolant temp....   should be around 215F... if this is below 170... it may make the computer take the car back to fast idle..  the sensors and the connectors for the coolant temp sensors have been known to go bad.. when they do.. the computer thinks the engine coolant just went to -20F..

throttle position sensor voltage...     this TPS  voltage needs be above 0.35 and below 1.0.. with your foot off the throttle...  work the throttle a few times...   the tps voltage needs to return to the exact same voltage... if not.. the car may rev like you describe.. as the ecm things you still have your foot on the gas...   if when you release the gas pedal you get different voltage readings...   i would look to see how worn the throttle shaft bore it.... with the engine off... open the throttle part way.. see if the shaft moves around.....

IAC...  idle air counts...   with the engine warmed up and idling... this readings should be 20 to 50 counts... this is how the computer controls the idle speeds...


take a look at the ends of your battery... are they swollen?????  pushed out and puffy...  might also be time for a battery... but what i am about to get at.. when the batterys go bad... they sometimes damage the alternator.. i have heard of alternators failing... putting out AC voltage and causing weird idle problems like you describe...   so having the charging system tested by someone with a proper testing machine... most machines test for AC  outputs... there should be none... alternators put out DC... any AC output just makes the ECM crazy..

air leaks into the filter to throttle body ducting...   power brake booster starting to go bad...  intake manifold gaskets starting to leak... usually under the plenum... the upper half...