Hey guys, i had my car in the shop for like forever they were putthing the front cover of the engine on...anyways..ever since i got it back.. it takes FOREVER to gain speed after like 120mph...before it use to clim pretty fast...at the same strecth i use to hit 155mph, now im having trouble hiting more then 130 mph !! my brother who was behind me said the car was throwing alot of black smoke compare to before...any ideas guys ?

p.s. i noticed that the last 1,000 rpm its slow in every gear and it dosent reach 6k if i hold it in gear...running to rich or something ?