I have a hyper .21 8 port race engine and when I start the car it idles fine but when I sit the car down and drive it out about 15 feet and back the engine is revved really high and my temps are close to 300f. I have taken the engine aart to seal the carb, backplate and HSN housing with RTV sealant but dont know what else it could be. I have just recently ordered a new fuel tank and new tubing to replace, can someone advise any other possible causes.