Inaccurate RPM reading

Has anyone seen this before, I just recently replaced my computer and chip (Hypertech). Now i noticed my RPM's way off the charts. Idle's around 1,250. (Normal) but noticed when i kicked it down it was up around 7-8K when i was jumpin on the highway. Now this is a stock motor so there is no way this is accurate.
Plus when it is rev'd up a tade, reads 4K ( for an example ) but sounds as if its 2K. Hardly even stroken. Other then that the car runs excellent

probably the computer or the chip then. the rpms are read from the coil, but I don't believe that would be the problem. Where did you get your computer and chip at? I'd see if you could exchange them.

Dont think its neither, ran the stock chip untill my hypertech came in and was the same. Besides since i have replaced the computer alone,(previous issue) the car runs better then it ever has and better yet with Hypertech chip, only complaints i have is pumping 93+ oc fuel wich can hinder the wallet but has the same millage. Baiscly very happy with the performance, just thought it was odd seeing the RPM's off.

when did the rpm issue start?

Honestly, didnt notice it untill the other day, But when i was having issues with idle/richness before i replaced the ECM is when i noticed the RPM's reading higher then what they really where. Now the idle is normal but when kicked down there in accurate. Was thinking switching over to a higher spark coil. It still seems to ping with 93 oct.