Training & Nutrition - trying to gain speed, strength

i started riding in feb this year after being off the bike for many many years, i have rode mainly public walk jog trails for 4- 5 months. usually 20-40 miles at a time 2 3 days a week 16- 18 mph pace . then i got where i did 100 one day. i was trying to get strength up and speed for group rides all on the trails . i usually ride 16-20 miles hr now .
i usually do 20-30 miles still 3 days a week or more. i am out doing the group ride thing now and have started heading to the country to ride alone where the hills are . as i knew it would i have found riding on the road really is harder rough roads terrain etc . i have done some very hard hill routes with groups and so forth and did them i was happy . i use high quality sports drinks and gel if i am on a long ride.
anyway i feel like i have hit the wall and i am looking to get where i can do 25 mph pace or greater on flats and fly up the hills consistently like a race training ride would be. any reccomendations on my personal rides training etc that can help me get through this slump i am in. i am trying to eat veggies and salads rice etc more and stay away from sweets burgers etc. does going vegetarin help you be leaner and stronger? i am trying to by fall or autumn or sooner be ready to train with the race group. mainly just to get in great shape and be strong enough to race if i wanna. i know strength training has plateaus i know i am there now. as i said i can fly on the smooth trail path system sometimes 30 mph on flats or greater yet the road is really taxing me. is this just the fact that i have left an esay environment and now i hav eto work harder to readjust. anyone has any routines they use that race far as hills and miles per week let me know.
i hav ebeen tring to do intervals etc and i am trying to pedal as circular and smooth a spossible. any pointers ther on pedaling or any at all will be great.

I am not one to give training methods or suggestions but want to point out that riding with racers is much different than riding alone or with a fast touring group. The testosterone level is much higher and it is not unusual for the group to tool along at 15-20mph and then jump up to 28 mph for a few miles before winding back down to 24mph They like to see people go off the back, it shows their superiority. The marked changes in pace are quite typical and something you have to be able to adjust to and recover for. It is not necessarily a personal thing, just the way a lot of them ride and typical of a longer road race. A kinder gentler group will reqroup periodically
but some don't and the fast guys just ride away. You probably want to look for some Cat 3-4 groups, as these you are more likely to be able to stay with. Vegetarian performance athletes have a hard road to hoe but it is feasible. Bike riding is calorie intensive and those muscles need a lot of fuel. Bike handling is important in group rides and racers will expect you to observe pace line etiquette and keep your bike in an expected alignment relative to riders around you. Steve