I've done judo for a good few years, but i took a year long break trying some other arts out (kratty and TKD which i dropped, BJJ and JJJ which i'm still doing) and I've recently got back into training judo several times a week.
One of my problems is that I'm very rusty with my forward throws (o goshi, harai goshi, tai otoshi, seio nagi etc) and the only one I can pull off in free sparring now is drop-and-flop seio nage. However, I don't know if this is because of my newfound enthusiasm for MMA or simply the fact that they are easy to do but i have become quite proficient at leg grab o uchi gari and double leg takedowns. I'm worried that I'll end up over relying on these techniques and get pwned by people who have sacrafice throws, guard work and guilotines at high skill levels.

What I wanted to know is wether I should simply drill forwards throws untill the rust falls off or if i should stop using any leg pick techniques in randori untill i have the basics sorted once more.

Advice would be welcome.

Drill the throws you want to improve. You can utilize them in addition to your leg attacks in randori.