rpms bouncing around weird

[gtcoup]

so i took the gtp out tonight to make sure my misfire issue was strait. i was going about 50mph and i was just coasting, off the throttle. i noticed the rpms were bouncing back between like 1300 and dropping to like 900. but parked idles normal? no codes or anything. any ideas?

 

[boostedcompg]

alternator going to poo perhaps

 

[gtcoup]

think so? its been getting cold so the past 3 days ive had to jump my gt. but i havent had an issue starting the gtp and its been sitting untouched for days.

 

[boostedcompg]

Worth a shot. That's what my jumpy rpms issue was

 

[gtcoup]

any other ideas guys>? could i just test my alternator on the car with a multimeter?

 

[SuperchargedFiero]

Did u find the problem ??

 

[gtcoup]

nah man . stumped