@ahmed12355
Not a big deal, chronic issue of Swift & in some Liana too.
Most important 100 Rupees ka Question......In which city are you located? Your connection from Engine bay to RPM Meter seems fluctuating might be due to loose wiring/connection, increased resistance or might be due to cluster needle or other such minor issues.
Meri bhee car ka RPM or speedometer dono ek saath kabhi kabhar ek dum ruk jata hay or khud ba khud sahi ho jata hay lekin meri car mey fuse box kay issues hain us ke wajah se hota hay. Apka kisi or wajah se bhee ho sakta hay