1993 Mazda Truck Help!

Computer problem
1993 Mazda Truck 4 cyl Two Wheel Drive Manual 130k miles

I have a 93 Mazda b2600i and have already had the computer rebuilt 1 time. Now, after turning in in to the shop (local shade tree mech) tp replace the coolant hoses under the fuel injectors and valve cover gasket, runs fine until it warms up then seems to want to rev up when stopped and can feel it surging (trying to speed up) in lower gears.

When I am stopped it revs up and down while brake is pushed in. If I leave it out of gear it stays idling between 1200 and 1600 rpms. Before last work was done, idled around 800 rpms.

At first thought it might be a loose vaccum line and even replaced pcv valve that seemed to help a little bit but did not come close to solving the problem. I thought maybe brake booster line but no luck there either.

I know I am not making a whole lot of sense but seems to me like the computer is telling it that it needs more fuel but the throttle linkage is slack and the auto choke? Or whatever it is called seems to be functioning properly.

Any help or input would greatlly appreciated. As I am sure you can tell, I know nothing about engines
Thanks
40Cal