JLG 50HT won’t start

I have a JLG 50HT boom lift that I can't get to start. It has the 4 cyl ford gas engine. It has always started alright until recently, It will crank and start fine, but then die after only a couple seconds. If I start it from the platform, it will run longer then die, or maybe keep running continuously until you try to do anything with it where it would rev up. (runs at idle from the platform and revved up from the ground). It acts like it's not getting enough gas, or has a stuck float on the carb. I've tried tapping on the carb like you would with a sticking float, but that hasn't helped at all. It has a new fuel pump on it and that didn't solve the problem. I took out the anti-dieseling solenoid thinking it was probably sticking, but it works perfectly fine and is getting power when it should. (I tried running a jumper wire directly from the battery to isolate it from any wiring issues) I'm running out of things to check and I'm getting really close to pulling the carb off and rebuilding it. Is there anything else I should check? For a little background on the machine: It has always had a little bit of a lack of power. When moving the machine at higher speeds, it really lugs the engine down. Sometimes to the point you think it is going to die so I let up off the drive lever. There have been a couple times after it has been running for a while that it doesn't want to shut down and will keep running on a bit after hitting the shut off switch on the platform. (sounds like anti-dieseling solenoid, but as I said, it appears to be fine). My oil pressure gauge doesn't work. Is there a safety switch that shuts it down if it doesn't detect oil pressure? Could it be something in the precision governor? any ideas would greatly be appreciated